All of a sudden our VM hosts started to show a "Host not responding" error in SCVMM 2012 SP1 console.
I had to deal with this somehow because new VMs had to be create.
First, I tried to refresh the host, which gave me error "VMM does not have appropriate permissions to access the resource".
There are many different articles, forum and blog posts about the issue, but none of that helped for me.
Fortunately the SCVMM environment was a small one and I just reinstalled SCVMM. This solved the issue.
But while reinstalling and reconfiguring SCVMM I noticed that Run as account for managing hosts was disabled... I guess this was the problem in the first place. So make sure to check this if you are expierincing the same issue.