This is happening to me, and besides being VERY annoying, it's interfering with my work. 
Running Fusion 5.0.2 on Snow Leopard (MacOS X 10.6.8), MacBookPro6.2, 2.6ghz Core-i7, 8GB RAM. I usually have two sessions running, one with 64-bit Windows7 Enterprise, the other with Ubuntu 12.04 64-bit (kernel 3.2.0-37).
The problem never happens with the Windows VM, it's always the Linux VM.
It always happens while I'm trying to compile files that are on the host filesystem (/mnt/hgfs/).
The entire session becomes unresponsive, I can't access menus from the minibar or anything else. The only way I can recover is to use the drop-down menu from the Mac menu bar, select the VM, and restart. I've tried suspend/restore, and it puts it right back into a frozen state.
Annoyingly, I can no longer copy/paste from the clipboard between that VM and host anymore (or that VM and any other VM), either.
I've re-installed vmware-tools several times, with no effect (VMWareTools-9.2.2-893683).
I don't recall this happening with the 32-bit version of Ubuntu 12.04.
This is very frustrating. Fusion 3 was rock-solid, and "just worked". The only reason I updated to Fusion 5 was because I needed Ubuntu 12.04, and that wasn't supported under Fusion 3.