Windows Vista has the ability built in to check for memory problems. Issues with RAM can cause your system to become unstable, lose data and fail randomly. Checking the memory should be the first step in any diagnostic process.
To access the Windows Memory Diagnostic Tool, you can go to desktop search box and type memory. You may also access them by using the Admin Tools area of the control panel or by booting off of the Vista DVD and using the Recovery Environment.
If using the utility from inside Windows you will be prompted with the option to restart your computer to begin the test or begin the test the next time you boot your PC. When your PC restarts, the diagnostic tool will begin and present you with a few test options: Basic, Standard and Extended. The Standard test is selected by default. Simply designate which option you wish to run.
These tests can take a while to complete so you may want to find something else to do with your time. The computer will report the results the next time you login. If you have a bad memory stick you should replace or remove the faulty module immediately. Memory errors can impact your Windows installation and/or performance.