I have only seen that error code in earlier versions of Video Studio, but I assume it has the same cause in Workshop. Unfortunately, the answer is in complicated English, but I can't really make it any simpler.
0x80040154 is a generic error, REGDB_E_CLASSNOTREG. It indicates that a required COM object class is not registered, or that something in the registry got corrupted. If the module/file that implements the class can be identified, you can repair the damage by running REGSVR32 [filename].dll from a command prompt (where [filename] should be substituted for the name of the actual file which is causing the problem.
Was there anything in the error message you received which actually mentioned a file?