Musicslot 20 is defective?

Happens every time I try to play tunes 20. There's no apparent problem with the file itself that stops it from playing in other programs.

More bizzare yet, if I try to overwrite O_MAP20M with another OGG file (namely, 2.0's version of the same lump), it still coughs up that error.

For the record, replacing tunes 20 does work. O_MAP20M was not changed between 2.0 and 2.1, something in 2.1 itself changed that rendered it incompatible.