If XP, you may be able to interrupt the startup and do a system retore. This will be done by pressing F8 after the hardware initializes and before the Windows logo appears. If you have another OS, post back but do try safe mode to see if it works there.
my parents have a used emachine T1742, 1.7 GHz Celeron proc. once the windows logo screen pops up, a blank screen appears. figured it was normal, waited for a minute or two and nothing happened. on sunday my brother bought a new webcam, so i went to control panel and removed the old webcam and its software. thats when the computer started having problems. first, when it rebooted, the screen looked like it was in safe mode. rebooted a couple of times, but still the same thing. then turned off the computer at the powerstrip. since then, thats when i've been getting the blank screen after the windows logo screen appears. one more thing, when the screen looked like it was in safe mode, tried to change resolution. instead of seeing 16bit, 32bit, etc., i saw 4bit. i've never seen that before. computer still runs after windows logo screen, and the blank screen appear, just can't see anything. don't know what to do. any help on this would be greatly appreaciated. thx