My Mac Pro OSX 10.6.8 is randomly freezing. It usually happens every 3-10 minutes. It usually, but not always happens when I access the dock, the screen will freeze, but the mouse will still work for another 5 - 10 seconds then both freeze for a few seconds and then all is okay. After doing this a few time then sometimes the screen will flash, just like when a pop up is blocked, then sometimes the screen will freeze light blue with short black lines all over it. Then it is frozen, but sound will continue to work. I can press power button and put it to sleep and wake it right back up and all is okay again. I did do a screen grab when screen was frozen, the image was of a normal screen. This has been doing this for about a week now. If I just turn it on and leave it alone it will be fine all day long. No problems. It seems some web pages cause this to happen more often. Any help would be appreciated.