Outlook resolving the wrong Exchange server

[E_S_P]

If you ping using the fqdn does it resolve to the correct IP(s) from these PC's for the correct exchange server? I dont know your topography but have you tried tracert if you are crossing routers/routing tables to make sure if you are ending up in the right place from these PC's.
Do they have any gateway addresses set - possibly from another network segment they may have been on ? Are you splitting the DHCP scope over multiple servers - if so any routers etc set in there. Tried a flushdns/release/renew ?
Do you have any DNS errors on your servers, and are they replicating changes ok - are the problem machines all connecting to the same server?

Good Luck & Merry Xmas !

[thegrassisgreener]

Why don't you speak to Riz at the CLC, he will tell you the problem streight away

[FN-GM]

@ E_S_P I have checked all that and its fine

@ thegrassisgreener I was surprised that Riz doesn't know I had him on the case right away he does think it could be a problem with AD. So how do you know Riz then?

Z