I Got the exact reason for this error.
Previously everything was OK.
Recently I changed my User Rights from Administrator to Normal User for My Windows XP Box due to Audit. Now I am facing the same problem which you have posted.
Then I reverted back to Original Settings, i.e. Normal User to Administrator.
Conclusion : This problem is attached with User rights, nOTHING eLSE
Yep - user rights is the true reason. I've fixed user rights in the registry for HKCR/TypeLib key and all subkeys.
In my case I've got this problem for both Administrative and Common User accounts. So - I've added 'Full Control' rights for 'Administrators' group (don't forget to check 'Replace permission entries on all child objects') and resolved the problem for Administrator account.