Try this
I have heard of instances similiar to yours and have a few reasons why your compouter might be doing this. One reason might be that the contacts for your ram cards are some what dirty, causing a bad connection between it and the motherboard. Another reason may be that your RAM cards died, leaving you with 1 working one. Still another reason may be that Microsoft Windows has a corrupt registry entry causing your computer to incorrectly use your ram. My bet is that your Ram cards are either dirty, or dead. Try using Memtest86. You can download it at
Memtest86.com - Memory Diagnostic. Try that first. If you don't want to try that program and are currently running Windows Vista or Windows 7, you can try using the built...