Hardware :: Power Mac G5 Will Not Wake From Sleep / Fans Blowing Full Blast

I just bought a new dual 2.0 ghz power mac G5 about 2 weeks ago. I set everything up and dowloaded all the updates for everything, and then about a week into using it the problem started. I left for work and when I got home that evening after the computer had been asleep all day, it sounded like the computer was taking off from a runway. It would not respond at all to the keyboard or mouse so I had to shut it down by holding the power button on the front of the unit and then start it back up. I called tech support but they had me turn the option off that puts the harddrive to sleep when possible and then turn off my screensaver. Well it was fine again for about a week and then it happened agin yesterday, not once but twice. I looked on apple discussion boards and there is alot of this happening. Well I took one guy's advice that seemed to know what he was talking about. I restarted holding the command-option-o-f keys down, then prompted the computer to reset the v-ram, and two other things he suggested to reset that I cannot remember. Then I restarted, trashed the energy saver prefs and ran a repair disk permissions task inside OSX. Well that is where I am now, and it has not done it again, but I am still trying to find out what exactly is going on here. I just spent $2000 on a machine and it appears messed up and Mac has no answer.