I have a good deal of experience working with Windows servers on network security related issues. The problem you're facing is probably related to IE's security settings. Other options are DNS, firewalls, etc.
I'll be pleased to work through this problem with you.
I have experience with respect to Windows OS patching and upgrade, IE upgrades, .Net application upgrades and can solve your IE related issue if given a chance. I hope to hear back from you.
Regards,
Sreekar.