I have run in to a strange issue on a number of ONTAP 8.1 simulators. After working with the sim for several days, both with PuTTY and System Manager, the simulator just hangs.
First time, it happened when I tried to log on to System Manager as a Windows domain user. I logged on through the VM console in the vSphere client and ran "cifs domaininfo" to check the domain health. The console session just froze - couldn't even use Ctrl+C to get the prompt back. Nothing else to do but to reset the VM from the vSphere client and everything worked fine after doing that. I ran all kinds of cifs commands without issues after the cold start of the sim.
Second time I had a hanging System Manager window, I did a "cifs resetdc". Guess what...frozen CLI and restart from vCenter.
Third time I had a suspiciously acting sim, I tried a number of CLI commands (except cifs) and when I finally decided to do "cifs terminate" the CLI froze again.
Seems too much to be a coincidence: it was very closely coupled to the cifs commands.
We are running the sims with version 8.1X47 on ESX 5.0. There are no error messages in /etc/messages during this time frame - I can just see the restart.