Mac Pro :: 10.6.8 Random Restarting - How To Stop It

I own a MacPro, running OS X 10.6.8. Several weeks ago it began to restart on its own, right after I turned it on. I ignored the issue and continued to work with it for several weeks.  Suddenly yesterday it began to behave funky again, to the point where I cannot work with it at all. I turned on the computer, and few minutes later, it restarted on its own for several times. The point where it restarts is random, sometime in the sing in section (when you place the password) or while I work on some program. I was trying to run DiskWarrior, and the machine restarted on its own again! 

I am also using part of this Mac as a PC, so I tried restarting on PC to see if its only on the MAC side, but it didn't make it through, it restart again before the windows icon appeared. Then after several restarts on the Mac side, an error message appeared, on the grey screen before the apple icon appears. It is all writen in code and it says something like: panic (cpu 0 caller 8x2aaf41): Machine check at .... (the picture is in my iPod but I don't know how to bring it into my computer). By searching this forum, I read I could try by reseting the PRAM and NVRAM, but I wonder what the consequences are when doing this. And if I try reinstalling the software, would I still be able to keep the PC side intact? Cause I still need to access the PC side as it is? I was able to run a backup for the Mac yesterday, but I couldn't for the PC.