I used mp3tag on a trial basis. All the files are 64kbs wma files. I used mp3tag on one directory of 6 gigabytes worth of files, and changed the file title ID tags. This worked fine, and the files played. This group of files were the ones currently loaded in my Sanya player.
I then tried to open a larger collection (around 15 gigabytes I think) in mp3tag. mp3tag crashed, I believe after selecting all files, and then pressing the 'Generate Tags' button. After the crash, all files had lost all ID tags, and the bit rates were set to 0. I didn't try to play any of these files, only thinking I'd have to use mp3tag to fix up the title, album, track, etc.
I dl the rest of my collection into the same directory as these, as well as copies of the files I mentioned in the first paragraph. Total size was around 25 gigabytes. I then broke the directory up into a number of temporary directories, each less than 10 gigabytes, and used mp3tag to change the Album, Artist and Title ID tags, based on the directory structure and file names. I then did a second pass to reset the track numbers based on the numbers at the beginning of each filename. Everything proceeded without error, although, after selecting the 'Generate Tags' button, and after the program displayed the 'Generate Tags' control screen, there were never any files listed. However, after starting the generation, the process proceeded, and I could see the appropiate tags were changed when the process was complete.
Today I finally tried to play these files, and all files are unplayable. Windows Media says they are corrupt, XMplay just doesn't play them, and GoldWave cannot determine the file format. This is true for the files marked with 0 kbs bit rate, as well as those correctly marked 64 kbs.
My trial period is over, so I cannot try any remedies with it. Needless to say, this has been a major disaster!