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

Windows will prevent you from deleting a file that's in use by a running program. If you can't find or shut down the program a different approach is needed.

AVG Anti-virus keeps telling me that I have a threat in the file C:\WINDOWS\cdsnp1.dll. AVG can't quarantine or delete it - it says that it cannot access to the file. If I try, it tells me something about the file being in use. What do I do?

This is likely one of the many manifestations of a very common problem. No, not the virus - I honestly have no idea what that is. I mean the inability of a program, or even you, to delete a file because it's in use.

In some cases Windows prevents you from deleting files because they're in use by some program running on your machine - often Windows itself. Deleting it while in use by a running program could crash your machine, or worse.

So what if you know you need to delete a file, but it's in use from the very moment you boot your system, and no matter what software you shut down it's still "in use"?

Windows also provides the ability to perform actions when it boots - before any programs are running. How this is specified is fairly obscure, and not something you want to deal with directly (it's buried in the registry, if you're really curious). Fortunately, there's a free utility to do it for you.

MoveOnBoot is a free download that allows you to rename, copy or delete a file the next time you reboot your machine.

When run, MoveOnBoot asks you to specify a file:

MoveOnBoot - specify filename

In this case I've selected the file c:\t\pagra.txt.

Hit next, and you'll get a choice:

MoveOnBoot - specify action

"Do not delete any Windows system files or your system may become unbootable ..."

It's called MoveOnBoot because the most common, and perhaps safest action is not to delete the file, but rather rename it or move it to a different folder so that the program that eventually tries to load it won't find it. However, you can also instead make a copy of the file, or truly delete the file, if you so choose.

In my case, I'll select "Move", and then it asks:

MoveOnBoot - specify move destination

I've left the location the same (c:\t), but simply changed the name of the file.

Finally, MoveOnBoot confirms what it's about to do:

MoveOnBoot - confirmation

Even though it says "Start", it simply schedules the action to occur the next time you reboot.

Now, when you reboot your machine, once it comes back up, the file specified will be renamed, (or deleted or copied, depending on what you specified) before any other program has an opportunity to place it "in use".

CAUTION: you can really hurt your system using this utility. Do not delete any Windows system files or your system may become unbootable and you'll need to reinstall Windows from your installation media.

Use this utility with care.

Article C2828 - November 2, 2006 « »

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.

Not what you needed?

Dan Ullman
November 3, 2006 9:09 AM

While it does not work 100% of the time you can often delete a file by opening windows in Safe Mode.

November 3, 2006 7:29 PM

If you have a download manager and the file has been downloaded, clear the download manager and try to delete the file.

November 4, 2006 11:56 AM

Thanks again Leo this is a nice utility to keep on hand so that when "Safe Mode Doesn't work" there is another way to try and remove that file. Oh! I get it, use this utility instead of "Safe mode" and there is only one "1" reboot of the computer and job done.... Sounds productive;-) and I like the renaming rather than remove (delete in Safe Mode) as this can eliminate mistaken loss of work when later someone on the net is screaming lost data with a file name you remember "deleting" but now renaming!

Thanks again Leo...

Les Rylett
November 5, 2006 1:37 AM

I use a small programe called UNLOCKER ASSISTANT. A search on the internet will find it.
It gives the ability to get rid of the link, move or delete

Paul Masters
November 5, 2006 5:11 PM

I also like to use ForceDelete which performs, as the name indicates, a forcible deletion of a file. It too is dangerous if the wrong file is deleted. ForceDelete is available FREE from softpedia at

Steve Myers
November 6, 2006 5:10 PM

I prefer to slave the harddrive and then run a scan. Nothing is running on the harddrive while slaved and AVG can clean the file in question usually.

A. Orcan
November 7, 2006 7:28 AM

I've been using unlocker, another free utility to delete files in use and it has never failed me. It is a "must have program", but must be used carefully as you have the power of god on all your files with it... Sometimes I may not even know that a file in a directory listing is in use and when I try to delete it, exlorer menu pops up with unlocker option ready to stop any relevant process and deletes the file(s)immediately afterwards. I used almost all available similar programs, but this one beats others by far. For comparisons and features see: "" and forget about junk and unnecessary file deletion problems.

November 7, 2006 12:59 PM

This program wii get rid of any file. However, why not just copy the suspicious file to a floppy temporarily. Then delete it from your system when in safe mode. Then reboot and if ther is a problem related to its absence, copy it back from the floppy and learn to live with it!!

March 9, 2007 6:14 AM

My IE7 was hijacked and I spent a week fruitlessly with anti virus programmes trying to remove the file/s that I had identified. No good. Then I chanced on this programme, 2 minutes later I deleted the file and now I'm hijack free..!! Brilliant programme would have paid for it if necessary.

delayed revenge
May 1, 2007 2:37 PM

Go to the address below and download Sysinternals Process Explorer

Open the program, and then;

1) Click binoculars icon, type program name (for example closeme.exe) click search
2) Click the process name you searched for
3) On the main window, right click the highlighted result and click "Close Handle"

Now you can delete or rename the program !

June 11, 2007 1:33 AM

thank you leo!!!!! that program is a miracle. i didn't think i was going to find a way to solve this problem.

Gord Campbell
August 23, 2007 3:24 PM

When I click on the MoveOnBoot link, I eventually wind up with a .MSI file, which Windows does not know what to do with. When I went to the software author's web site, I got a .EXE file, which said it could not find the .MSI file... This was just an exercise in frustration.

September 8, 2007 7:10 PM

I had a problem deleting a malware DLL that seemed impervious to the above ideas. I finally got rid of it by setting the security permissions to Deny Execute. Next time I rebooted, the dll was unable to load, and could be deleted.

September 18, 2008 3:28 AM

Thanks for this, worked a treat on a file that McAfee marked as a Trojan but could not delete.

September 26, 2010 8:08 PM

Hi, this is a little long, but I hope you could help me. And yes it is related to moveonboot, since it won't delete the file I need it to.
Somehow I got the SecurityTool virus installed in my computer, after an exhausting war against it I manage to delete it. But afterwards it seems that a good number of malwares found their way in my computer. One of them took the name of one of my folders and added .exe at the end, and is this particular one I'm trying to delete, it says I can't because is in use somewhere.
I read the other article about procexp and downloaded it. I've found the handdle (there were 6 with the same name) but after I click on it everything is highlighted and I don't know which process to end.
So I saw this article and downloaded moveonboot, I've installed it, and so far so good, but when I try to delete it, or rename it, moveonboot denies me the acess or something like that. In other words, it can be done.
Any antivirus, antimalware, antispyware can delete this thing... So if you could help me, I'd be reaaaaaally thankful. Seriously!

November 4, 2010 11:37 AM

Hi, this program formatted my hard drive.

Mark J
February 20, 2011 1:30 AM

This often works when MoveOnBoot fails.

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