Format HD or Not – MSHTML.DLL Error

Explorer has caused an error in MSHTML.DLL I receive this error when windows opens, and I can’t do any thing. every time I close the window it reappears. I happened when I did Speed Disk in Norton Utilities. ME is my OS I reinstalled Windows ME once everything worked fine. A few days later I ran speed disk, now I have the MSHTML.DLL error again. Do I need to format C-Drive, and reinstall windows. Thank You, Calvin