Don't give up ! Sounds like you need to do some investigating into your hardware.
It could be any one of several hardware related issues rather than a software prolem:
1 - Failing power supply: Dowload and run Everest Home V2.20 from: http://www.majorgeeks.com/download4181.html
Look in Computer > Sensor. The +3.3V, +5V and +12V should be
within +/-5% of their nominal values.
2 - Overheated CPU: In Everest look in Computer > Sensor. The CPU temp
should not be over 50 degrees Celsius when idling. Overheating can happen
as the result of a failing CPU fan or excessive dust buildup there.
3 - Bad memory: Download the Memtest86 CD ISO file and burn it to CD from: http://www.memtest86.com/
Set your BIOS so that the computer tries to boot from the CD/DVD drive
before trying to boot from the hard disk. Memtest86 will thoroughly test the RAM
endlessly. Let it run for, say, 5 passes. No errors should be listed.
If multiple errors do show up and there is more than 1 RAM module, test each individually
until you can isolate the bad one.
4 - Failing hard disk: Download and run the Hitachi Drive Fitnes Test at: http://www.hitachigst.com/hdd/support/download.htm
Again, download the ISO file, burn it to a CD and then boot from it.
Navigate the menus and do a full test. DFT can also access the S.M.A.R.T.
reliability information that is created and stored within the hard drive itself.
These 4 tests will go a long way to confirm whether or not your hardware is in good shape.