Yeah, that's really not a lot to go by. You might have better luck contacting Roxio directly through their technical support.
One thing could try as a work around is to approach the adding files from a different direction. For example, if you were drag-and-dropping, use the Edit->Insert Into Project menu item or visa-versa. Also, you might try changing the name of the file or putting it into a directory with a different path. In particular, make it the old DOS-style 8.3 filename and path without any spaces or special characters, etc. You might also check the version of the mfc42.dll file in your windows\system32 directory, (mine happens to be 6.0.8665.0 - Tuesday, December 07, 1999, 8:00:00 AM) and see if there is a newer version you might be able to replace it with.