I recently ran into an issue where the DRAC on an R610 froze up when the OS became unresponsive.
The system is running VMware ESXi 4.1.0 (Dell version) and froze up, and I'm not sure why. When I tried to connect to the DRAC, it was also unresponsive. I am using the dedicated NIC for the DRAC, and was able to ping the IP address but not connect via https or ssh. My only option was to hard remove power using our remote power switch.
The point of the DRAC is to be able to remotely access the system when the OS is not functional. If an OS component can take down the DRAC, it calls a lot of recovery plans into question and I have lost a bit of faith in the DRAC. I have seen this before when sharing the network port with the OS, but not when using the dedicated NIC.