Problem with drivers for Ati Radeon HD 5850

[funny_creature]

Hello! I was experiencing sudden restarts with my PC and all the tests showed that my hard disk was failing. It was 4 years old, so I decided that purchasing a new one will solve my problems. But when I installed Windows 7 Ultimate 64-bit and installed the latest drivers for my card (from AMD's site) the sudden reboots reappeared. I tried differrent versions of the drivers, including the one from the manifacturer's CD, but the result was all the same. I tried installing Windows 8.1 Pro, but he problem got worse, because that OS intsalls all the drivers automatically, so I reverted back to Windows 7. The fact that the problem happens when i install the graphic card drivers is what is making me thinking that there's some kind of problem with them or the card itself. There's no problem accessing safe mode or normal mode, when there aren't installed drivers. The drivers were removed with Driver Sweeper. I updated the chipset driver, but that didn't help either. The configuration of my system:
DualCore Intel Core i3-540, 3066 MHz
Gigabyte GA-P55M-UD4
RAM - 4 gb
BIOS - Award Modular (07/31/09)
I'll really appreciate some help, because I'm running out of options here.

PS. Forgot to write about that. When there're installed graphic card drivers and in safe mode (because in normal mode I can use the PC for 5 minutes max. before the reboots start) I see a lot of 7001 errors - Service Start Operations. But no services were stopped, because i checked them in "Services".

 

[funny_creature]

Update: Since starting this thread, I've tried different things, including updating the bios drivers. I also removed the card, cleaned all the dust (there was many inside the fan) and put it back. The PC run the OS longer (for about 15 minutes) before the reboots started again. Thought that it"s a good idea to make a clean install of Windows, because of all the use of Driver Sweeper, the sytem couldn't find some files ("MOM.Implementation" for example ) and CCC couldn't open at all. The problem remained. I'm now thinking it's a hardware problem. Maybe the PSU, GPU or the motherboard is failing. Right now my only option is to have the PC tested at a local shop. If anyone has any idead, please feel free to share them.