What software did you load before this started happening?
Try this for starters:
In safe mode go to Start -> Run -> Msconfig - this will bring up the System Configuration Utility.
Under the General tab - put a dot in Selective Start Up, then put a check in System.ini and Win.ini
Go to the Win.ini tab up top and click on the + to the left of Windows - then uncheck any line that starts with "run" or "load" (without the " ")
Hit Apply then OK - go ahead and reboot.
If it reboots into normal mode then it's a program trying to load when windows loads that may be causing the problem.
Let's see if this works first though.
Hope this helps.
