I've got a bit of an odd problem with W7 in a corporate environment.
We have a fresh Active Directory child domain and started installing the first clients into the domain. The domain controllers in the domain are both DNS and DHCP servers. The clients are installed in another network and taken to the domain network where they are taken into AD.
About 60-70% of these clients have MASSIVE internet problems. When a user attempts to access a website, it takes about 2 minutes for it to load - the browser sits there doing nothing. At the end of the delay, the site loads almost instantly. On the remaining 30-40%, browsing works without a problem.
The clients access the network over a proxy (MS ISA) in another domain (the users must authenticate themselves with credentials in the other domain).
I've tested DNS - a DNS query is answered almost instantly from all involved DNS servers. The client's event log is clean.
A wireshark TCP dump shows that the client contacts the web server immediatly after the user enters the URL in the browser - the client also receives an answer from the server. After the initial gets and response, NOTHING happens related to that connection on the network side. No single packet is found in the connection. Broadcasts and other traffic are logged meaning that the NIC works fine. After a long wait, traffic for the website continues and the site loads instantly.
No VPN software is installed on the computers; the clients are currently running McAfee 8.7 managed with an ePO server.
I've tried disabling Remote Differential Compression to no avail. I've also disabled IPv6 and QoS on the NIC side, reset the network settings and disabled TCP auto tuning.
I've confirmed the DHCP settings, checked Windows Updates and can't find the problem.
Does anyone have an idea what the problem could be? This is driving me and our users crazy.