Password Validation from off-site DNS server

Hello all,

My name is Casey and I am a Network Technician for a large Healthcare organization in North Central PA. We have several remote locations that we service in this area. One location that we service is maintained by a full T1 connection. The problem that we are running into is the time for the DNS server that is offsite to validate the password takes to long for windows to recognize so an error message comes up saying that there was no DNS server to validate the password. However the password is actually validated. We are able to see our servers on the network by doing a find-computers and typing in the name of the server we would like to find. If you open the network neighborhood their are no computers shown in this view. Here is our setup of this Network:

A T1 line running from North Penn to our site. Then a T1 line running from us to the Hospital that owns North Penn. At that Hospital we have a Domain server and exchange server that handles their email accounts and they actually log on to that network for email purposes. We have The trust relationship setup between our domain server and theirs. Reason for this is we have mainframe applications that this hospital uses from our location. Basically we contract out to them to use our mainframes for data storage and such. The trust relationship allows us to manage their networks from our site. Managing things such as TVD, ArcServIt bakcup, etc. So when someone logs onto the network from north penn the route it is traveling is as follows:

They go through our router (to access certain servers and mainframes here)
then they also connect to a router at the other hospital to actually logon onto the domain server there for email, Internet and such.

So the rough milage between all these facilities is approx. 200 miles for a round trip.

My question is this, Are their any registry edits that can be done on the workstations to increase a timeout period to wait for authorization from the DNS server? Any changes that can be made on the DNS server to resolve this error?

I thank you for your time and i know this is kind of a sketchy map of the network, but their so much more to it and their is just not enough room here to lay it out in full detail. But the rough sketch should be enough to guide you. Again i thank you for any input in this matter and hopefully someone has ran into this out their and knows of a fix.

Sincerely,

Casey klesa