Any idea what would cause that? The files appear to be fine and the ID3 v1 tags are read by every other program i have.

Thanks.

Sounds like ID3v2 tags are being misread. Please remove foo_id3v2.dll and use Tag to convert your tags to something better, like APEv2, or ID3v1.

Those are supposed to be ID3v1 tags though. Winamp and Tag&rename report no ID3v2 at all. Any idea why the might have ID3v2 plugin kicked in like it did?

Here happened the same, all the file information in tags appear the same as Mike Giacomelli shows

I also had a number of mp3's that had this problem. But I fixed them by removing all the tags and manually adding them with foobar2000.
As a side note, the first of them did have ID3 v1.1+v2 and when adding them to the playlist with foobar2000 0.586 it would crash. But in foobar2000 0.7.4-0.7.6 the title and genre fields were filled with the block characters.

Winamp and Explorer do not support v2.4 tags, but I don't know about Tag&Rename.