Multiple instances

After shutting down guest when restarting error says cannot run as guest is running already.

There is nothing running.

 

.
A rogue process exits. You should be given the option to start it anyway. Just do that.
.

 

I had this happen once, too, after my 80 lb. Lab jumped up and yanked the Firewire cable out of my Mac (I run my .hdd on an external drive). If Constant's suggestion doesn't help (it will most likely do the trick), just reboot your Mac and restart Parallels.