BUG: “Old format or invalid type library” error when automating Excel

Although my OS is english (!) version, running the english (!) version of Office, I get an error when opening an Excel workbook via COM. The error message doesn’t help locating the real problem:

Because my locals are german, and the Office Multilanguage Pack is not installed, Excel tries to locate the german language pack and fails.

Solution: set your application’s CurrentCulture to en-US, and it work’s like a charm!