Very Slow Start with borrowed licence when connectet to a network

After updating from ArcGIS 10.0 to 10.1 i've got the following problem:

When i try to start ArcMap/ArcCatalog with a licence i borrowed, ArcMap needs about 30 minutes to start.
The Licence Server of my University provides a concurrent use licence, which is accessible from outside the university network only through a VPN-Connection.
The very slow start happens only
a) when i am connected to the internet when starting ArcMap
and in addition
b) when i am not connected to the university network (via VPN or when i am physically connected to the university network)

So ArcMap starts quickly when i
a) interrupt any internet connection, start ArcGIS and restart the internet connection again,
or
b) when i connect to the licence server via VPN, and then start ArcGIS.

Tracing the processes with a task manager, ArcMap starts and hangs then waiting for an network I/O process.
Observing the IP Connections, ArcMap seems to try to connect to the Licence Managers IP with the correct remote IP and Host (27000), but does not get any response, because it is not in the network.
It tries 4 times with different local ports (53099, 54000, 54001, 54003) within some seconds and then waits for about 30 minutes befor giving up and starting ArcMap with the borrowed licence.

I tried to add the Licence Server Name and IP to the file C:\Windows\System32\drivers\etc\hosts in as described in
http://forums.arcgis.com/threads/591...icense-offline
but without success.
Any idea how to decrease the timeout for the lookup for a remote licence server, so that ArcMap uses the borrowed offline?

I am using ArcGIS for Desktop 10.1 AP1 on a Windows 7 64bit machine.