That sounds like a hibernate/standby feature in the OS you are running in the vm. I have a Windows vm at work where we have enabled the standby functionality via a policy for all Windows machines (and thus my vm as well). After some idling Windows will go into standby mode which looks like VMware Player (which is what I use at work) suspended the vm. I have seen this in VMware Fusion on my MBA with my Windows 8 vm as well. You can easily fix this by disabling these options (I only changed it for my Win8 vm; changed the energy saving profile to "high performance" which disables standby).
Btw, Fusion 5 does not support the saved state functionality (it's called Resume) in OS X that was introduced with Lion (Mountain Lion has it as well but iirc it is disabled by default). Fusion uses it's own suspend/resume functionality.
Message was edited by: treee