Random black screen on boot

Hi, Heres my dilemma, I have a Acer 5050 that chooses to boot to black screen, (video fine on external monitor, but in low resolution). I updated xp, updated ATI driver to new one, set resolution to medium, rebooted and video comes back on notebook fine. Then I came back 2 hrs later and black screen again, I plug in external monitor again and its there, low res again. I set video to factory default settings in ATI control panel and rebooted, video fine again! Seems like if I leave it for an hour or two it goes back to black screen. Could this be a battery issue? I see the battery is very weak. Acer has a management program on it to control video, etc. I don't know if that could be suspect too.

 

I have no problems once I can get it booted with live screen. I've found if it comes up black to shut it down holding the power button down(not good I'm sure) then restart, and then the screen comes up. I did notice to cmos battery time is not keeping up, but I doubt the cmos battery would cause the black screen on boot. :confused