Cannot activate Unity on a college network

We have 20 3.xx licenses and we have successfully activated Unity in the past on several occasions for use in our lab. This was using Win XP (if that's significant)

The college has upgraded to Windows 7 and now we cannot now activate Unity.

The serial numbers have been deactivated. We have successfully activated a copy of Unity on a laptop (that goes through the firewall) and so it looks like its our build of Windows 7. Nobody here knows what to do about this and time is passing. Emails to support are slow and the whole thing is fustrating.

Logically the evidence would suggest that it is the activation process that is failing.

Does anybody have any new lines of enquiry we could persue please ?

Thank you.