Windows 2003 Standard + SP1 + ISA 2000

[xnex]

Here's my problem: I'm administering two windows 2003 servers. One month ago, I applied a SP1 on both machines, and this managed to scr** things up. What's the problem?

First to explain roles of servers. One of them is an AD controller, while the other is backup controller. First server also has ISA 2000, Sophos Enterprise manager and some other stuff installed. Also, it is a NAT server for my intranet (150 computers or something like that), with private address range.

Not to complicate things any further, here's my problem. After patching the system with SP1, I'm experiencing strange network problems. For 90% of users, there's no problem, since they use standard applications - mail, web, nntp and stuff like that. Basically - stuff that don't require persistent network connections.

But, for people like me, and some other in my organization, who use applications that require persistent network connections to function properly (putty for example - SSH connections), it's been crazy. After a very short period of iddle time, all my connections are terminated.

For example, if I use putty to connect to one server, and after establishing the connection, I use like Firefox for like 1 minute, leaving putty unattended for 30-40 seconds, when I come back to putty, my connection is immediately terminated. Some other applications we use here also require persistent network connections and it's been very frustrating always registering again and again after only 1 minute of iddle time.

Since I didn't know how to solve the problem (I even suspected on ISA being the guilty one, but no changes were made on ISA server), today I removed SP1 (on the NAT machine only, on the second machine i leaved SP1 be), and after that, everything is working very well - no termination of iddle network connections, no problems at all. I can leave putty for hours and it won't be terminated.

I hope i managed to describe the problem without many complications (english is not my first language), and hope that someone has a solution for it, because i don't want to leave the first machine unpatched!

Thanks,

Nenad