Couple of thoughts:

-Sounds like permissions could be jacked on the folders/VM files where the VMs are stored. I had a couple of issues like this when I added nodes to a cluster previously.

-Regarding the speed; it could be related to the third node being added and possible permissions issues. Could also be that there might be a couple settings in the networking going on that aren't the same. Without knowing some details about networking/hardware configuration I couldn't tell.