RMM is misreading some of my ID3v2 tags (they're read just fine by WinAmp and emplode).
Misreading in what way? Are the tags Unicode?

Furthermore, I can't even update the properties of some files in RMM, because it somehow detects these files as being read-only, when they clearly aren't (checking file properties in Windows Explorer).
You also get this error if the file is open in another application -- for instance, the preview thing in Explorer in Windows XP, or even RMM's own MP3 playback window. The error message should be more helpful really.

Peter