Do you have any pre-installed hardware diagnostic tools that came from the manufacturer, or did you build this system yourself.
My diagnostic tools came preloaded and run once a month and are found here:
Click
Start 
,
All Programs ,
PC Help & Tools , and
Hardware Diagnostic Tools.
This checks all of my hardware and all of my memory.
Its a version of PC-Doctor 5 for windows that came pre-loaded.
WDE.