Can a website cause my computer to get a "blue screen of death"?

The dreaded "blue screen of death", or BSOD, appears when Windows determines that a very serious error has happened, and it can either no longer continue running safely, or it's become so "confused" about what it should be doing that it can't continue.

Typically whatever you were doing at the time the error happens is lost, and your only recourse is to reboot your machine.

A BSOD "should" never happen. Windows is actually architected to handle errors in much more graceful and less abrupt ways. If a program does something wrong, for example, only that program should be affected; Windows, and your machine, should keep running without a problem.

But there are two common places where Windows simply cannot protect itself enough, and thus must rely on the last-resort BSOD to report errors:

• Hardware failures - most commonly power supply, memory or motherboard problems. When memory fails or when a power supply is on the verge of failing completely not only can Windows get totally confused about what it should be doing, but it can also end up trying to do things that it simply cannot or should not do.

• Device driver bugs - in particular kernel level device drivers. You probably won't be able to tell which is which, but some device drivers operate at the same level of privilege as Windows itself. A bug in such a driver can result in a BSOD. (Some drivers can operate at the same privilege level as applications under Windows, so if they have a failure they may crash, or an application may crash, but a BSOD is infrequent.)

There are other issues that can cause a BSOD, including bugs in Windows itself, but those BSOD bugs are very infrequent these days.

Note that there's nothing in the previous discussion about websites or the internet. A BSOD is something that happens on your machine, because of a problem with your machine or the software on it. If you regularly experience a BSOD when you visit a particular web site, then that web site isn't directly causing a problem, it's simply causing your computer to exercise some software or hardware on the machine that has the problem.

So what do you do?

Well, to start with it sounds like you've been doing the right things:

• Keep up to date with the latest critical fixes from Microsoft.

• Keep up to date with the latest driver updates, either by visiting Windows Update, the hardware manufacturer's site, or preferably both. (Updates can often be found on one or the other, but not always both.)

• Run hardware diagnostics.

The BSOD looks like a bunch of gobbledygook to most folks, but there's often an important clue or two in the mess. For example:

In this example, the BSOD is actually pointing at a specific file that may be related to the error. If it's the same file every time, then that suggests a software or driver issue. Figuring out what that file does (often a quick Google search will do), may lead you to the driver in question. If not the software, then it may indicate a problem with the hardware that driver controls.

Unfortunately it's only a clue, not an answer. The file may be totally unrelated to the problem.

Often diagnostics that come with computers aren't quite as thorough as we might like. There are two tools in particular that I would suggest, depending on your situation:

• Memtest86 - a very thorough memory testing utility. There's been a slow increase in problems with memory, and this tool should ferret out if you have a problem, and exactly where. Memtest86 is free.

• SpinRite - an extremely thorough hard disk testing and recovery utility. SpinRite is not free, but it's the most exhaustive hard disk testing and recover utility I know of. If your problem is due to bad sectors on your hard disk (which could result, for example, in a corrupt copy of Windows or its drivers), there's a fair chance that SpinRite won't just tell you about the problem - it'll fix it.

BSODs can be very difficult to track down. In many ways it boils down to detective work, and I hope that with some of the information above you'll be able to get a few clues as to what's going on with your machine.