Helping people with computers... one answer at a time.

Registry cleaners will often report multiple errors on every run, even after having recently 'cleaned' the registry. The registry is ... complicated.

A program which you recommended - [name removed] - promises a free download and a free scan. After installing it ran a scan and found over 1,000 errors on my PC and fixed only one, then ask you to purchase the program to fix the 1,000 errors. Fair enough, all they promised see above.

Now to the real question : Why is it that the running of a PC constantly creates these errors? Is it not possible to write a program like Windows which runs clean without cluttering up the registry and what have you? Would it really be that complicated to write an OS which does not constantly leaves all kinds of garbage behind?

I removed the product name from the question because I did not, in fact, recommend it. My assumption is that the reader misinterpreted an ad (which is provided by Google) as a recommendation on my part. No matter what site you're on it's important to understand that advertisements rarely represent endorsements, and they certainly don't here.

The answer to your real question - "why?" - does, indeed, get complicated.

But my recommendation turns out to be very, very simple.

Long time readers may recall my somewhat controversial position that the best registry clean is no registry cleaner. By that I mean that I do not recommend regularly running registry cleaners at all. I may use them when attempting to resolve certain types of problems, but in my experience they're simply too powerful for frequent or casual use, and often cause more problems than they resolve.

"... I do not recommend regularly running registry cleaners at all."

They're also very inconsistent, which I'll talk about in a moment.

So that's my recommendation: don't use that product - or any registry cleaner for that matter - unless it's indicated when attempting to address a specific problem you're attempting to resolve.

Now, about the registry...

The registry is nothing more than a managed database; a very simple loosely structured database into which programs including Windows can store and retrieve information on a system-wide or per-user basis.

One problem is this concept of "loosely structured". In reality, there are very few rules as to what goes into the registry. There are some rules around where things belong in the registry, but even those aren't necessarily applied consistently, and certainly not enforced.

Given that there's so little definition around what programs use the registry for, that leads us directly to the hardest question of all:

What does it mean for a registry to be dirty? What's an "error"?

And that, in turn, leads to the most egregious problem with registry cleaners: they make assumptions about what is and is not an error, and what is and is not dirty or clean.

The good news is that a lot of those assumptions are often correct.

The bad news is that a lot of those assumptions are often at the very least questionable, and frequently wrong.

For example, if the registry has a reference to a file that no longer exists, that might be considered "dirt", but we can't really call it an "error" because it might well be legitimate.

Let's say you edit a document in Word, and word puts that document in its list of most recently edited files, which is kept in the registry. Now you exit Word, and later delete the file you edited. Word never had a chance to remove the file from the list - so it remains in the registry - but the file's been removed. That's certainly not an error, and even if we thought that it was, I'd be hard pressed on where to place the blame.

Another common scenario is uninstalling software.

It's not at all uncommon for software that has been uninstalled to leave behind information in the registry, on purpose. Some applications choose to leave behind your settings and customizations so that information is not lost should you re-install the application. Others may leave behind the fact that they've been activated, or that they're only a trial version set to expire on a certain date.

You can certainly argue whether that's right or wrong or how it should be handled, but once again it's not technically an error since it's purposeful. Even then, it simply is what it is.

And whatever it is, registry cleaners don't agree on how to deal with it. One may call it an error, another may warn, and a third may ignore it all together.

One will call it garbage, and another will not.

And they both may be right, depending on how you look at it.

Now, I've no doubt that there are many applications out there that don't use the registry properly - having written software that uses it myself I can say that it's very easy to get it wrong, and easy to consider it unimportant to clean up when deadlines loom.

But I'll also say that much of what applications do correctly, or at least intentionally, is often labeled as an "error" when in fact it is not.

And yes, for the record, I do believe that the entire concept of the registry, while initially a laudable approach to solving several different problems, has gone far, far astray. Like most geeks, I now much prefer the Linux-style approach of using plain text files in specific ways for keeping the same kinds of information currently kept in the registry.

Article C3838 - August 14, 2009 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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8 Comments
Ken B
August 14, 2009 8:31 AM

Nice to know that Google's context-sensitive ads would place an ad for a registry cleaner in an article explaining why you don't recommend registry cleaners. :-)

Another problem with the way that the Windows registry has evolved is that even Microsoft keeps changing where system settings are stored from one version of Windows to the next.

Yeah, I kind of figured the Google ads would target that way. Smile
Leo
14-Aug-2009
vincent
August 16, 2009 2:42 AM

"Now you exit Word, and later delete the file you edited. Word never had a chance to remove the file from the list - so it remains in the registry"

Sounds like the registry's just a datadump...
Why doesn't the OS manage this a little better?

Not sure what you would expect to be "better". There's no clear answer what the OS (or anyone) should do. The OS cannot assume that just because the file is gone the application doesn't still expect or need the registry entry.
Leo
16-Aug-2009
David
August 18, 2009 6:31 AM

If you must use Windows, every IT guy I know uses and trusts CCleaner (used to be called Crap Cleaner) www.ccleaner.com

It is consistently the most thorough, error free clean up and registry fixer available (and it's free for personal use :))

Read the reviews and I'm sure you'll get the same enthusiastic responses

Or, use Linux.

Paultx
August 18, 2009 11:01 AM

One common argument registry-cleaning software creators (or advertisers) use to entice prospects is that registry leftovers, clutter and stuff will somewhow make systems at least slow at times, and prone to crash some day... Leo, what's your thought on that?

I disagree as to the severity and the frequency of that problem. Yes, it can happen, but it's not nearly as common or as severe as the manufacturer's make it out to be. The fact that there may be unused registry entries typically has only a miniscule impact on overall performance.

Yes, you'll always hear from someone who swears up and down that a registry cleaner magically fixed some problem or improved the speed of his computer by some amazing percentage. It's possible, and why I don't dismiss them completely - but I only recommend them as a last resort when trying to solve a problem.

In my opinion registry cleaners are too risky for the average user and if you're not actually experiencing a problem using a registry cleaner has little practical value.
Leo
19-Aug-2009

steven
August 18, 2009 4:57 PM

Now CCleaner keeps deleting my quick launch toolbar. After many years, I deleted it. I settled on Eusting registry cleaner. and removed all the other Free cleaners from my other test computer. Too late, I noticed none of my USB flash drives work anymore. They use to work with the Native USB drivers I had a month ago.

Charles Tilley
August 19, 2009 9:17 AM

Registry cleaners are nothing but junk.They promise to speed up your machine,but I don't notice a difference. I do use CCleaner,but only to securely delete temporary internet files. If you must use one,Windows Live Safety Scanner is a good option. Some of these other cleaners,memory optimisers,etc. aren't worth the page they are on. Some of them can even severely damage your machine.

john n.
August 19, 2009 7:58 PM

Most of the problems you describe with registry cleaners are due to lack of proper setup, or lack of knowledge.

There are things called Ignore Lists. Even if something you need gets deleted once, it need not again. Blindly doing anything is mindless.

Ccleaner shows every file/ registry entry found in a scan to review BEFORE you hit delete. Many are obvious. And with a good program, nothing is permanent unless it states so first. You can undo changes easily.

Just like a hammer, if you don't know how to use it you're going to cause yourself some pain. I understand the need to play down to the lowest common denominator. "Average User" doesn't necessarily mean we need to dismiss something out of hand because we're to dumb to learn...

Eddie Baart
November 29, 2011 9:03 AM

Ignore my recent question about registry cleaners. I have now found the information in your archive.
Thanks
Eddie

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