I have a pool of machines that users access daily. The pool is well provisioned, the parent machine is robust and my environment is not being stressed. However, I'm regularly seeing one to three machines that are nobody is logged into, consuming large amounts of guest memory. I can shut them down and when they come back, they seem to be OK. However, this is happening with regularity, and not with the same machines. I take care of the snapshots and recompose the pool regularly with a fresh snap, and ensure the parent machine is happy and performing well before taking a snap. So I'm at a loss as to why idle machines are chewing up so much memory.