I just found the nature of an annoying bug in
licq: it gets the byteorder wrong on
UINs on some incoming messages, which results in messages appearing to come from
nonexistent users. (I.e., a message from user 0x1234567 would appear to come
from 0x67452301.) So, if you get messages from nonexistent users and want to
find out who sent them, just convert the UIN into hex and byte-swap it.
Or wait for a fix.