ESXi 5 (essential), 2x poweredge R610, 1x Equallogic PS4100, 2x powerconnect Dell switches in stacking mode. 5 servers in production - exchange (100users), sql (Fin.soft), PDC, spiceworks and file server and win7 with some stuff. The usage of hardware is not even close to maximum.
Installed server 2012 with 2 network cards. Copied something from my pc to it, rebooted and got disconnection with error from vsphere client... weird... trying to reconnect... nothing happens, host not found! This is where I start feeling that my manhood is at stake... 2 minutes from this point I'm getting reports that there's no network in all building... at all. Can't access any web interface of any device and/or ping.
After connecting directly to host I've managed to remove that server and network resumed to work.
What gives? The new server didn't had anything on it... didn't even configure IP or join it to the domain... nothing at all. Last thing was vmware tools installation and copy 2Gb ISO on it.
I did, however, had weird stuff with win7 week ago. It just didn't get anything from DHCP. So in the end I just added new virtual adapter on it and deleted the old one.