I am running Leopard (Not Snow Leopard) on a 2005 Power PC G5 (Pre-Intel) I keep getting the gray screen that comes down and tells me to restart my machine in 4 languages. I have tried PRAM/NVRAM, SMU and Reinstalling the OS but no change. Sometimes this happens 5 times a day. The fans also sound like they are working overtime while the screen is coming down. Please help, this is getting to be really annoying. Thank you.