Test the memory. I believe that Vista has a memory tester, but I like Memtest86+ from www.memtest.org . Obviously, you have to get the program from a working machine. You will download the .iso to make a bootable cd. You will need third-party burning software to do this such as Roxio, Nero, or the free ImgBurn . Burn as an image, not as data. Then boot with the media you made (you may need to change the boot priority in your BIOS so that the optical drive is the first boot device). The test will run immediately. Let the test run for an hour or two - unless errors are seen immediately. If you get any errors, replace the RAM.
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