For a while now an orphaned VM is in the VM list of an ESXi 5.0 host on our VMWare HA cluster, how it got there? Nobody knows :)
The Remove option is unavailable, and it is impossible to drag it anywhere else. The disk it is linked to is used by a VM with the exact same name and is up and running without any problems.
Logged on to the host where the orphaned VM resides and checked with;
.....and checked if this would display something strange, which is not the case. As a running VM is using the disk and is linked to the same location re-registering the VM doesn't make sense.
So Step 1: Move all VM's to different hosts and put ESX host in maintenance mode, rebooted the host...no result. After the reboot the orphaned VM is still visible in Virtual Center and ofcourse not on the host when checking on the console.
At this point corruption of VCenter database passes my mind. I deleted the host from the cluster and added it again. After this the orphaned VM is gone.