Ouch. This error has bothered me for a couple of days now, and I finally found a solution. I kept getting this error when I was building a depolyment project.
First, you should try Microsoft's Knowledge Base article on the problem: http://support.microsoft.com/kb/329214/EN-US/.
Didn't work? It does for some... but it didn't for me either. If you are still having problems... you have another dll that needs to be registered again. "regsvr32 ole32.dll". That last command solved the problem for me.
I recently removed a bunch of applications off of my machine, I'm guessing it got hosed somewhere in the process.
- Dan Lewis