We don't have a fix for the 64-bit OS (XP or Vista) problem yet. At some point, we'll release an updated version that will fix this problem, but I don't know how soon that will be.
In the meantime, I wonder if you could open up an MS-DOS window and convert the files that way.
Click on the Windows Start Menu, and type "Command" in the "Start Search" box. The following command would convert a file to MP3:
mp3towave -3 "path_to_mp3"
You have to put the entire path to the MP3 file, so if the file were in your My Music folder, the command might look like this:
mp3towave -3 "C:\My Music\Yesterday.WAV"
This info in in the help file, but here are all the flags:
-3 (Convert to MP3)
-C (Convert to WAV)
-M (Convert to WMA)
-G (Convert to OGG)
Note: Audio Converter Pro can convert to OGG, but MP3 to Wave Converter PLUS can't.