Hi there,
I just noticed that you're having a problem with ISO tags and I was having the same issue too.
I don't know if my condition is similar to yours, just thought to let you know you're not alone.
What confused me was the fact that version 2.32 didn't have a problem with that, maybe because it was supporting native codepage, but then again it didn't support any kind of unicode.
Well now if I really, for some particular bizarre reason, want to have native codepage I go to that version but since I'm not using Winamp anymore (well rarely, and that's what made me see the problem in the first place) and I switched to Foobar, I am a happy person! 
EDIT: Sorry to bump such an old thread, I did notice it was old, it's just that Florian is busy right now and I thought this might help.