Hmm… I actually haven’t tested that on Windows, nor has anyone of my friends I sent it to, only on Linux. It would be very strange though if that was an OS-related problem, but who knows. I will have to test it there.
Adr, have you tried the new version? Is the bug still there? I haven’t made much of changes to the crouching code, but again, who knows.
EDIT:
Hmm… That gives me a clue on what’s wrong. The crouch levitation has to be a high value (though it does look like it’s too high at the first glance, but it’s not) because otherwise you won’t be able to climb stairs. Once I figure out what the flying deal is of course. Anyway, my guess is that instead of setting the levitation value it increases it in every step. That might be the case. I’ll dig into that, but first I must get into Windows and see if I get that glitch as well.