Hi,
It's a familiar issue, and it's usually due to an ActiveX control on your computer having been uninstalled or deleted, while entries for the add-in program or ActiveX control still remain in the registry.
Quicktime or Netzip plugins are the main culprits.
Go to start/run, and type 'Regedit'
Navigate to the following subkey:
HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer\Plugins\Extension
Highlight this subkey 'Extension', and choose 'delete'.
Please don't confuse with the 'ExtensionS' key further up.
See the <a target="_blank" href=http://forums.techguy.org/attachment.php?s=&postid=247841>illustration</a>.
Close Regedit, and reboot.
Good luck, Tony