Comp keeps restarting

[Alpha]

In most cases system restarts because of smps issue. Try checking whether its working properly or not....

[Ashwin]

Did you install any new hardware? like RAM, Graphics card, Mouse or anything else.

Security softwares can cause crashes too. I remember PC tools FW causing BSOD when I tried to install Returnil a year back.
When I removed PCTFW the issue disappeared. Similarly your security software may be blocking some driver/software service.

Recently I installed Clean-mem on my dad's PC and whenever I tried to run CM, the computer restarted. I use KIS 2011 on that computer.
But Cleanmem works fine on the other computers. So its incompatible with 1 PC

Try performing a system restore to see if it may solve the issue or ask a hardware technician to check your computer.