If you get lots of blue screen errors or random crashes in Windows, it could be that you have faulty memory. This should be one of the first things to diagnose as it is very simple to do so in Windows Vista as there is a built-in memory testing tool.
To load the Memory Diagnostics Tool run from the run menu (Press WINDOWS KEY + R to access this):
You can choose either option, depending on whether you have work in progress (which needs to be saved first). On the next restart your PC will then load the memory testing application before Windows loads. This will perform detailed tests on your system memory:
Once this is finished, Vista will load back up as normal and present the test results. If there are any errors, it is worth replacing the faulty memory stick to ensure you have a smooth running system.