How many hosts in your cluster?
Is your faulting host able to talk to any of the others?
Can you vMotion to a different host?
In my situation, one host couldn't talk to 3 or 4 of the 7 hosts in the cluster but I was still able to vMotion.
Otherwise kind of a Catch 22 - You need to put in Maintenance mode to fix vMotion, but you have to vMotion to put it in Maintenance mode.
Would turning off HA or DRS on the cluster help?
