we've six new HP ProDesk 405 computer in our environment and some problems only with this new machines:

DriveMapping-connections are disappearing randomly sometimes and we can't disconnect or reconnect this mappings. (red cross, not always all mappings)
Computer has to be restarted always it appers.

On all machines we updatet to Novell-Client: SP3 IR7a and set FileCaching to OFF (also on our Servers).
We also tried to update LAN-Firmware and drivers or installed another network card - doesn't solve the problem.

All other Clients have no problems like this.

I searched forums, etc but cant solve this problem.

Has anybody an idea what I could do to solve this problem?