There is a lot that can cause that
check your event log for errors
start / settings ( might just go to control panel ) / control panel
admin tools / event viewer look at the system log
all so DL this program. When you run the program it will create a bootable floppy diskette, they also have an image file you can burn to a cd if no floppy. leave the floppy in the floppy drive set you bios to boot from the floppy / leave in the cd drive and set your bios to boot from the cd
to go to bios ^^^^^^ when your notebook boots you should see press F1 / F2 / DELETE to enter setup
have you tried putting the battery back in ?