We use SharePoint 3.0 for quite a bit of document collaboration. Unfortunately, when using Internet Explorer 8, an error is thrown when we attempted to upload multiple documents within SharePoint. The error details mention Library Not Registered.

Luckily, there is an easy fix:

• Open up any MS Office 2007 product. In my instance, I used Office 2007.
• Go to Help>Office Diagnostics.
• Run diagnostics. This took about 5 minutes to complete.
• Return to your SharePoint site. the multiple document upload tool should now be working. Apparently, this fix re-registered any .DLLs that were causing the error. I love easy fixes!

Thantos Office 2007