That suggests it's related to a plug in of some kind. The only one I've got is Excalibur. I've actually got two identical systems, both with Vegas and both with Excalibur. It's only doing it on 1 of them.
Excalibur would not be the cause of that error. I'd try reinstalling Vegas on the bad system. Just install over the top first and see if that fixes it. If not, you may need to uninstall/reinstall.
If nothing seems to help, it may be that the permissions on the affected system are messed up. I know very little about this aspect of Windows, but I can attest to strange behaviors on an otherwise-normal system.
What I discovered is that there is a way to "reset" this aspect of Windows back to default. It's discussed in this thread.