After Ububtu or other VMs hangs, parallels can't poweroff or reset them

and if I force quit the parallels session either through Apple's menu or "sudo kill -9 " the process through a terminal, it stays and the memory can't be recovered.


This happens the most often with ubuntu. win xp seems much more stable on parallels.

Any way to reclaim the lost memory eaten by parallels or force parallels to quit completely?