Starting this morning my Mac Pro has been giving me a random black screen on my two monitors and when I have music playing and it does this black screen I can hear the music likes its completely froze. I have done the AHT test and it did not find anything wrong but I'm out of ideas on what it could be. Also note that now can take a time or two of hard reboot for the monitors to come on and for my mouse to get power meaning my keyboard isnt getting power. Thanks for the suggestions

Mac Pro 2.4ghz quad core
2 21" monitors
5GB ram
Running 10.5.8