I have a problem with my iMac 2 GHz Intel Core 2 Duo (2 GB 667 MHz DDR 2 SDRAM), running OSX 10.6.5. OSX crashes and freezes all the time. Nothing works anymore. Sometimes it just freezes, and I can only move my cursor, but nothing reacts anymore. Sometimes the screen blacks (or sometimes blanks) out or shows the weird moving colours as shown on the photo I just took below: After restart, it often happens again and again. Then the iMac is fine for a couple of days, before it freezes again. Can anyone diagnose the problem from the info above? Thanks in advance!