There are some ideas here on beep codes. It depends on the motherboard.
The next thing to check is the RAM. If you have more than one stick, take one out and continue to use it as normal. If you still have a problem, swap them over and try again. If it's OK, you know which one is the culprit. If it's still freezing, it's not the RAM.
If you only have one stick, download and run Memtest for at least 3 hours, preferably overnight.
-------------------- OK OK I can't go any faster! aaaaaaaaaaaagh!