Hmm. In the VM configuration menu, go to the options tab and then optimization. Click Enable Adaptive Hypervisor and Tune Windows for speed.
Also with your VM open and all, open the activity monitor, go to the system memory tab, and when the flickerin happens take a screenshot and post it.
When i went in to the configuration, I remembered that I had turned on Adaptive Hypervisor earlier in the day, before the flickering started. So I turned it off and now, no more flickering! Seems like that may have been it. Thank you again for all the info!