MacBook pro doesn't recognize password

I'm on a MacBook Pro, OSX 10.7.2, 2.4 ghz Core 2 Duo, 4gb RAM. I opened it yesterday to find a new gray screen with a request for user name and password, which it rejects. It doesn't start in safe mode. I cant get in to the computer at all. Any suggestions

Since you're running Lion, are you able to boot to the Recovery partition? (Command + R) If you can boot to the recovery partition you should be able to run Disk Utility to check the hard drive and if necessary, change your password.

Thanks for the advice. I got into Disk Utility by booting holding down the alt key. But I don't know what to do once in there. Can you guide me through the steps needed to change the password? Thanks.

Tofaette said:

Thanks for the advice. I got into Disk Utility by booting holding down the alt key. But I don't know what to do once in there. Can you guide me through the steps needed to change the password? Thanks.

Click to expand...

Follow these directions: LINK

Great! Thanks. Gonna try it in a bit - really hope it works, but I don't understand how the computer got into this mode in the first place.

Reinstalled Lion, now running 10.7.3, no help on the boot screen issue.

My question is what made the computer do this in the first place? It happened after I shut it down, not merely closing the lid to sleep. Any ideas?