I use the Windows XP Virtual CDRom Control Panel regularly. It's a great utility for mounting .iso files to a virtual cd rom drive to avoid having to burn them to an actual disk. Many large development tools (especially from MSDN) are distributed in .iso format for download. However, one of the most frustrating errors with the tool is the ambiguous "Mount Failed" exception that is sometimes thrown.
I received that error this morning while trying to mount the Visual Studio 2008 Pro image. I remembered running into this exception on numerous other occasions but couldn't remember the exact cause. After a small amount of googling and experimentation I found that my problem was caused by whitespace in the file path to the .iso I was attempting to mount.
Removing the whitespace from the file path (I just copied the .iso to the root of my C:\ drive) fixed the problem, so this time I decided to blog it in case I run into the problem again in the future.