Servers: Windows 2008 R2 Enterprise, Hyper-V, one virtual machine is office domain controller, another slice is Exchange.
On Monday, on of our techs performed a driver update on the Hyper-V's NICs. Starting then, mail would not flow inbound. About the same time (not entirely sure), IE stopped working properly. Tuesday evening, we found that, if we modified the MTU on the network to 1464, we could get mail flowing. The change was made on the firewall, not the server.
Wed/Thu: IE was working except for some HTTPS sites (ex: https://orders.dominos.com
). Others worked fine (https://secure.experts-exchange.com
). Lots of stuff was done to fix this - including replacing the firewall - EXCEPT removing the updated NIC driver.
Friday: Still happening on all systems on the network (not just the servers).
Does anyone have a clue? Could it be the NIC driver on the Hyper-V? How would that cause other workstations to fail? I am going to look into removing the driver update but I am not yet convinced it is the problem (not this one anyway).
The NIC is an HP NC382i and the driver is 188.8.131.52.