It doesn't really help to get help that you don't know the exact errors.
Anyway, I'd run dxdiag (the DirectX diagnostics program) and see what it says.
Hi, I recently built my own computer and installed windows 7 for my OS. The computer works perfectly, runs smoothly, and has been generally great...when I am doing everything but playing a video game. It first started when I began playing the online game EVE. Every 10 minutes or so the screen would flash green and grey and then freeze. After several dozen times of this I began to notice I could hear an alert sound from my computer right before it crashed.I soon discovered I was getting several error popups that seem to only occur when I play EVE and seem to crash the computer. One says something like "accession error code:#### kernel". Another error that sometimes comes up is (and I can't remember it completely) "Failed to access something" and it asks me to "Abort, Retry, Cancel". Well I stopped playing EVE and it has worked perfectly since. Yesterday I decided to try a new game called DAY Z. Within 5 minutes of playing it the computer crashed in the same fashion it did with EVE. If anyone has heard of these symptoms before, please let me know if there is anything I can do. Thanks
(also I ran the windows RAM and HDD test and got zero problems with both)