The registry server can be different from the vob server and the view server and eventually your own station.
if the registry server is not accessible through network .. the clearcase doctor analysis say :
Problem: Regions "windows" and/or "unix" unknown on registry server "cmserv".
Solution: You must be within a network region to refer to VOB or view storage directories.
If it is not the case, and pinging the server reaches it correctly, verify that your credentials are coherent between your station and the registry server. The albd server service is working with enough privileged rights. Ports are authorized by the firewall.
using the albd server account:
<ClearCase_Home>/etc/utils/credmap your_registry_server
You can make a simple test accessing the registry server by listing vobs, regions, views
cleartool lsreg
For ClearCase regions.
Ideas: regarding your station under Windows seven: ensure you are connecting the right registry server (the one under CC8).
Execute a <clearcase_home>/etc/utils/creds and compare with what you have on the XP station and with what you have in the server.
Installing Wireshark, ok it is a little bit tricky at this point but, I already found network issues with analysing the communication behaviours between the station and the server.
Complements: when you said it works on W7 7.1.2 to CC8 registry server, it means you are able to start a dyamic view on a VOB and the checkout command is working fine in your context. (I suppose here your registry server is also your VOB server and your view server is your station.)