some of the sql-statements are simlpy wrong ie. "select * nbnew from.... " where
"nbnew" is not allowed to be and so on...
furthermore there is an error in the handling of a message, people who've sent a
message can delete it in their outbox completely, so that it will be deleted in
the recievers inbox too.
another misbehavior is the reply-button viewing a message, which has been sent
by the user itself (outbox). it's senseless and not working  properly, cause the
reply message is not adressed to the sender, but the receiver of the inital
message. (could be solved in the template as well by hiding the replybutton if 
userid==fromid.)

i've looked over all php.files and corrected the errors, so that i'm able to
upload a fixed version of the module. if you are interested in please send me a
PM.
regards 
christian