Recently I was working on a problem where a customer received that error message when trying to open a TFS work item list in Excel triggered from Team Explorer.
The error did not appear when opening Excel right away and accessing a TFS query.
I was checking Process Monitor to see what was going on underneath using the comparison technique that I learned from Mark Russinovich.
It turned out that Excel 2007 was installed and it’s COM Classes are registered in HKCR\TypeLib\{00020813-0000-0000-C000-000000000046}\1.6.
In contrast when Team Explorer wanted call Excel through COM automation it used HKCR\TypeLib\{00020813-0000-0000-C000-000000000046}\1.7.
Obviously TFS was trying to talk to Excel 2010 instead which was not present.
So I rang the customer to discuss it further and it turned out that they installed Project 2010 to these boxes running Office 2007 that seemed to have added a newer automation class registry key for Excel though even though it was not even installed.
Anyway, deleting the key HKCR\TypeLib\{00020813-0000-0000-C000-000000000046}\1.7 solved the issue for the customer.
Project, Excel and Team Explorer work fine with that tiny little change.
My learnings: “When in doubt, run process monitor.” 
Comments
Anonymous
May 10, 2012
Thanks that helped. Had to do the same and it worked like a charm.Anonymous
May 29, 2012
Awesome - solved my problem that I have been battling for hours - thanks!!!Anonymous
August 26, 2012
Really worked out for me also...solved the issuse...thanksAnonymous
January 11, 2013
Thanks. Helped me a lotAnonymous
January 30, 2013
Thanks man, solved my problem too after hours of digging, Thanks a lot