I'm not convinced this is a hardware issue. I have a stock 13" 2011 MBP, and put in the Intel 510 250GB SSD, and immediately had issues with a fresh OS X install. Doing several reinstalls, and trying some of the suggestions here (SMC reset, PRAM reset, etc) had no effect on it - I was getting constant freezes, beachballs, etc.
The reason I don't believe it's hardware is that I put a Bootcamp partition on it with Windows 7 Ultimate x64, and it's been running flawlessly for a couple of weeks now. The problem is ONLY in OS X.
Have you tried upgrading to 10.6.7 in OS X?