First, you should try enabling JavaScript in the Internet Explorer preferences panel. When you have Internet Explorer open, go to Edit > Preferences. Go to the Web Browser > Web Content pane. Under Active Content, check the option to "Enable Scripting", then click OK.

If you continue to receive errors about JavaScript being off and you have OS 8 or 9, it's possible you have a corrupt Registration Database. Delete the following file, then restart Internet Explorer:
Macintosh HD:System Folder:Preferences:PPC Registration Database