First try overinstalling IE6-SP1:
First, close *everything* via CTRL+ALT+DEL except Windows Explorer (includes
your AV program, Scheduled Tasks, Screensaver, and going offline).
Start>Run>IE6Setup.exe. Select Minimal - Custom; Select all the parts you
use, including OE (but none you didn't originally download) and overinstall.
Should take about 2 minutes. Reboot the computer.
Now, with AV and all other running processes still closed, check in at
Windows Update for additional updates and patches you will need.
To assure a clean install, your anti-virus application should be disabled
and all other running processes closed before installing anything, including
Windows Updates, and especially in Win9x.