I installed Lion the other day with no problems, and there has been at least one time that I shutdown the computer completely (not related to Lion). Today, I let Firefox update itself to ver. 5. After doing that the Firefox stopped responding, and I started quiting programs. I had to force-quit firefox. I then rebooted the computer. All I get is the sound of the video card fan in high-speed mode, and there is no signal to the monitor. The computer does not appear to boot any further despite repeated attempts. SMC, PRAM resets (pulling the power cord from the back) did nothing. Any other ideas?