Pop up blocker - HELP

System

Question.
On our existing server, W2K TS6.1 All of our users have no problems accessing (unless they have a 3rd party popup blocker which we instruct them to disable) the popupblocker in IE that comes with XP SP2 does not catch any teamsite functions.

We are upgrading to a new server W2K3 TS6.1 basically the same config files, same TS version, just different OS. When we test with XP client machines the IE windows popup blocker catches every new window that needs to be opened

I know you can configure it to "allow" from the specific host but it seems weird that everythign works fine on our old server. it is also a pain to have users do this when the old system did not require it (our userbase is not technically strong). Does it have somethign to do with it being a new version of IIS that comes with W2K3

Interwoven support gave the traditional response of remove all spyware and popupblockers refering to Knowledge Base Article: 52684

The only other factor is that the current server that works popupfree is in our 172 network and not firewalled, the new one is in our 192 DMZ and firewall rules are in place to open the applicable ports to our userbase.