[justinator]

Lucky. I have to restart perhaps once a day/every other day as the UI becomes unresponsive. Sometimes putting the computer to sleep means it restarts by itself, or I have force power it back on.

[coldtea]

With headless VMs with a few GB, or some huge-ass VMs?

Could it be something unrelated, like Spotlight getting stuck, or some hungry app? I guess you've consulted Activity Monitor and such