MP3 files won't play in iTunes (Vista), but will play in WMP/iTunes (Mac)

I have a strange problem that's starting to get incredibly frustrating!

Have a wonderful Mac (powerbook g4 1.5 ghz), got a new PC recently, running Vista and iTunes 7.5.0.20, and transferred my iTunes library over.

I've found that a significant number of MP3 files (maybe 5% of a library of 5397 songs) refuse to play on iTunes, but play just fine in Windows Media Player or in iTunes on my Mac.

The problematic files exhibit the following symptoms:
If I double click one of the files to play it (or hit the play button), nothing happens
If I set album art to show for the selected song, I get the mesage "Album Artwork Not Modifiable" in the album art box
If I try to convert one of the files to MP3, I get the error "Error occurred while converting the file "foo". An unknown error occurred (-50)."
The problematic files have artist/album/title info, but they have nothing listed for "Format" "Channels" "ID3 Tag" or "Encoded With" (the labels don't show at all in the "Summary" section of Get Info

Any suggestions? Right now, I'm thinking of re-encoding the problem files on my Mac, but that's a pretty kludgy workaround. Ideas would be appreciated!

Thanks!
Daniel

Message was edited by: dccarroll