From what I can tell on these forums, this is happening to other users on these forums, too.
-upgraded to Fusion 5
-suddenly, (Ubuntu, but probably other) vms hang - one vmware-vmx process takes more than 100% of one CPU
-hack fixes:
--seriously, run the QuickTime screen recorder, full screen - magically the vmware-vmx process drops well below 100%
or
--run TWO different Ubuntu instances; as soon as the second one is running, both seem to make headway
-reverting to Fusion 4 didn't fix this
-I turned off stuff I didn't need:
--printing
--3d graphics
-VMware support yesterday told me that it was "stuck" processes as seen in Terminal / top
-Today they acknowledged that there was a known issue with VMware 4.x that was supposedly fixed, that this seems to track
Suggestions welcome.