There's little worse than a blue screen crash. One minute you're working away at your PC, engrossed in some important project: the next, your PC is rebooting and any unsaved work has gone forever.

This kind of crash is usually caused by a buggy driver, Windows service or some other low-level operating system component, but Windows won't always give you a precise file name. And so you're often left trying generic fixes, removing recently installed programs, cleaning up your hard drive, fixing Registry errors and so on, just hoping that you'll get lucky and find the cause.

WhoCrashed takes a different approach. When you first run the program it'll automatically download and install Microsoft's Debugging Tools for Windows, a very powerful troubleshooting package. It's also quite large at around 17MB, so this may take a while if you're on a slow internet connection, but be patient. You only need go through the setup process once.

Once the program is fully installed then using it couldn't be easier: you just click the Analyze button, wait a few seconds while your recent crash dump files are being examined, then read the report to see exactly which files WhoCrashed blames for your recent instabilities.

We tried this on a test PC and WhoCrashed told us that uacreplace.sys was responsible for one crash. We didn't recognise the name, but a quick Google check told us this was part of a tool called Smart UAC Replacement: we uninstalled that and the crashes stopped.

You won't always be this lucky. Crash troubleshooting is a difficult business, and occasionally WhoCrashed will get it wrong, blaming core Windows components when the real culprit is elsewhere. Still, if your PC is unstable and you can't seem to fix it then WhoCrashed has to be worth a try - it could provide just the clues you need to fix the problem.