Cold boot. Just as the black screen comes up, before the "Windows" screen
appear, press F8 repeatedly - at two-second intervals. You should then be
offered the Safe Mode choice.
If that does not work for you, click START|RUN and type "msconfig" (no
quotes) <enter>. Click the BOOT.INI tab. Checkmark the SafeBoot box.
Reboot.
When done with Safe Mode, UNcheck that box. Reboot.