Macbook Pro loads and then switches to sleep mode

[introubleagain]

Hey guys, would really appreciate some help with this one.

I've got a MacBook pro, it's a few years old now, but it has been running great until today. All of a sudden, while I was working on the computer it switched itself into sleep mode. When I pressed the load button, I saw the login screen again (but it was very dim) before it almost immediately went back to sleep.

I turned off the computer by holding down the button, and now whenever I load the computer again, it does the same thing. It shows me a dim login screen for about a second before going to sleep.

I've got no idea how to fix this one, and would appreciate any ideas as to what the problem can be.

I've tried with the power cable both connected and disconnected, and I have also tried booting the computer from the power supply only, with the battery removed.

Thanks for your help!

 

[Kaveman]

Boot withe the S key down and see if the problem persists.

 

[introubleagain]

Thanks for the suggestion, but no change when I do that. I've also tried booting in safe mode and single user mode with no luck.