A) does DBCC memorystatus reveal anything?

B) review the SQL and windows error logs (especially around startup) for anything unusual

C) review hyperV and host config, especially everything related to memory (dynamic memory stuff would be first place to look). http://msdn.microsoft.com/en-us/library/hh372970.aspx.

D) move sql to a physical host to confirm that hyperV or host config is cause?