MacBookPro crashed with pixel disturbed screen and 3beeps
There is most probably a problem with your RAM.
You can run a full test on the RAM with something like Memtest booted off a CD. See here for Mac instructions.

You may find just one RAM module is corrupt and you just need to replace or remove it. It might also be that the RAM has become unseated, try taking it out and putting it back in again to see if that is the case.