crashes stop errors can be caused by many things it may be worth checking a few things if you have'nt already done so
have you installed any new programs or hardware prior to the error ?
do you get any error messages ?
have you performed full system antivirus and spyware/adware scans
if you wish to carry on with stress/load testing you will need to grab something along the lines of sisoft sandra which has a burn in wizard click here=
bare in mind though if it does find any weakness it could break the component