VMWare - Cannot find a valid peer process to connect to
I work a lot with VMWare Workstation, and tonight while I was doing some work on a lab environment, I realized that the VM containing my domain controller was not running. It had been running earlier, but now it was not. When I tried to start it again, I got the message "Cannot find a valid peer process to connect to". Google turned up all sorts of things, including people who said that everything was fine after they rebooted the host machine. Since I'm usually juggling three or four VMs at a time and each one takes around 8-10 minutes to shut down, I wasn't about to waste my time with that.

Instead I went into Task Manager and looked at the processes. I currently had two VMs running, one Windows 2003 server with Data Protection Manager that I'd given 1.5gb of memory to, and an Exchange 2007 server that I'd given 3gb to. In the Processes list, I could see three instances of vmware-vmx.exe, and two of them had a Peak Working Set that matched the amounts of ram that I'd allocated them. The remaining one showed a working set of 1.2gb, around the amount I'd allocated to the domain controller. Once I killed that process, I was then able to fire up that VM. Apparently it had crashed, but it had left a ghost process behind that was keeping that VM from starting up again.

So that's an easier way to go about it than rebooting your host workstation. Worked for me, but it might not work for you.  ¶ 11:21 PM