We need to take one step backwards in trouble-shooting first...
- When logging into the workstation, make sure you are logging in using a domain account, not a local-machine account.
- Since the IE settings are at the user level, any previous changes will not be there in the new domain account on that workstation, so make sure that the website is added back in as a trusted site or in the local Intranet group within IE.
If that still doesn't work, we'll start taking a closer look at the Windows 2008 Server. I have several here on my network, but my main webserver is still on Windows 2003 R2, so I'd have to setup a test site see what is going on.
One thing I "can" say for sure is that by default W2K8 is locked down significantly more than W2K3 was. For example, in W2K3 the firewall is disabled by default, while in W2K8 the firewall is enabled, bi-directional, and locked down tight. You need to specify what programs are allowed to communicate with the network before a lot of things start working. There is an advanced Firewall Settings menu where you can disable it temporarily, but off the top of my head I cannot recall how to get into it as it is not a normal menu item. On the other hand, be careful of disabling the Firewall Service. In W2K3/XP it was simple to test if communications problems were a firewall issue, as all you had to do was to stop the Firewall Service in the Services menu, but if you attempt the same thing in W2K8/Vista, it will actually shut down ALL network communications if you do that.