JC,
Because I can't duplicate what you are seeing, it would help if you could use another program and let me know what you see. If they behave the same then it is most likely not an MC problem..Also, please let me know what Operating System you have so I can try to replicate this.
Also, if you find that there are certain files that always fail with the '23' error, please email me one for testing. (steve @ jriver.com)
Extensive testing last night. Issues resolved, but not understood.
Test #1 (test box with WinXP pro SP1):Format iPod with WinXP as FAT32
MC9.1.199 didn't recognize drive as iPod
Ran iPod Updater 2.0
Format iPod with MC9.1.199
Transfer entire music library (no playlists)
No error code 23 messages
Available space accurately reported by iPod
Test #2 (real box with WinXP pro SP1):Format iPod with MC9.1.199
Transfer entire music library (no playlists)
9 (out of 360) files returned error code 23
Available space incorrectly reported as 27.3 out of 27.8GB
Test #3 (real box with WinXP pro SP1):Format iPod with WinXP as FAT32
Ran iPod Updater 2.0
Format iPod with MC9.1.199
Transfer entire music library (no playlists)
1 (out of 360) files returned error code 23 - different than the 9 from Test #2
Available space incorrectly reported as 27.6 out of 27.8GB
Test #4 (real box with WinXP pro SP1):Ran iPod Updater 2.0
Format iPod with MC9.1.199
Synchronize playlists (including "All Music")
No error code 23 messages
Available space accurately reported by iPod
FYI - although both boxes "look" at the same drive for the source music files (and cover art), the MC9.1 libraries are different. Therefore, in order to sync my real box with the iPod, I had to wipe the results from Test #1 off of the device. Otherwise, I may have determined that formatting with WinXP solved the issue.
I'm not sure why it works sometimes and other times generates errors. It appears that receiving any error code 23 messages will hose up my iPod with respect to remaining available size. All other aspects work (new file transfers, etc ...) but the "Table of Contents" (for lack of a better term) gets corrupted anytime an error code 23 occurs. This corrupted TOC is only cleared by wiping the slate clean (iPod update or WinXP format). Formatting from MC9 will not clear the corrupted TOC.
Finally, testing from two days ago (pre-test #1 above) resulted in accurate iPod behavior with MusicMatch Jukebox with the same files. All files transferred without error and size was accurately reported (I did a complete 'restore' of the iPod twice from MMJB).