Using zeppelins or boats freezes client

Can you give details of which ones cause the problem as I did a very through check a while back.

Any other information you can provide to help us track this down will be appreciated

I tried the Zeppelins from Orgrimmar to undercity and to Stranglethorn, I think i tried from Undercity to orgrimmar too not 100% sure.
And i tested one of the boats from Menethil harbor to auberdine and the boat from ratchet to booty bay, but they all crashed the client when it was supposed to zone in,
(after the Indiana Jones-style map animation)

My friend that found this after the v21 install crashed aswell between Orgrimmar into Undercity
(and they were unable to log back in, since the client kept crashing on load, so had to teleport them away offline on a Gm account, although their loginscreen says they are at the destination, so guess it's something with the actual spawning)

I don't know if this can be database related? Been installing and deleting the rev 21 database all evening testing ways to get it to run it's updates with as little errors as possible.

(edit. I'd love to be able to try the v.20 version and see how it works but haven't found a compiled version, and cant compile it myself, errors everywhere)
/P