I just found this topic and thought I'd add: I got this problem and it was seemingly due to the open-source software PDFCreator, which had installed itself to a subdirectory of C:\Program. I wonder if this is a bug with the installer system, because I certainly didn't specify that directory during the installation. This is pure speculation, but maybe the installer has a problem parsing spaces in directory names, and "Program Files" became "Program." Just a thought.