If you are certain it might not be a hardware problem, it might be a process problem.
Do a little test, Go into safe mode and leave it on like that for awhile. Does it still crash? If it doesn't crash then you know that its a process that is probably causing the computer to crash
ALso, Check event manager and look for the timeframe when the crash happened. Sometimes that will lead you to the process.
IF you can't localize the process using the event manager, You will have to stop all unnecessary processes then One by One start them back up.
There is also some programs that can check your system and registry for errors. Cnet I believe has one. If I Find it I'll edit it in in a bit.
Okay found some links that might help. BUT first.
GOTO Start/run/cmd then enter Chkdsk /f (check disk). Next time you start your computer it will check harddrive for errors and fix any broken sectors.
Advanced system care. I've used it once or twice. Did help out in some instances.
Advanced SystemCare Free - Free software downloads and reviews - CNET Download.com
This program should help you isolate the process that might be causing you a headache.
Startup Optimizer - Free software downloads and reviews - CNET Download.com
Oh, and after you've done all that and still a no go. Sometimes a bad windows update can cause problems. Roll back/remove windows updates back to the time the problem started and that might work. IF all else fails, Reinstall after you've checked the hardware aspects. Might be your only go.
If you have any questions on any of this, Just message me or email me and I'll walk you through.
Hope this helps and please respond. Would like to know if this helps or not. (hope you didn't get a virus. Check out the program Sandbox. This program makes it safer to browse the web IMO)