I did a search (although my search may have been less than perfect) and didn't find a thread on this, so here goes... Twice in the last 10 days my MacPro has locked up while browsing Safari. Fans go full speed and sounds like it's going to fly away. I have to hard shut down and when I do, the power light blinks off and on. No sequence, just off and on. I do a power reset by unplugging the tower for 30 seconds and pressing the power button to clear memory. Startup and all is good. I can't find anything in the logs that indicate a memory issue or possible graphics card problem. Any suggestions? P.S. I'm using an early '08 MacPro (2.8 8 core) with a WD SSD boot drive, 8 gigs of RAM and have the ATI Radeon HD 3870. I also ran Rember to test memory and that said everything was good.