After suspending a VM the whole Workstation GUI window hangs so it's impossible to interact with any other running VMs.
The whole window needs to be killed, along with all other VM tabs, because it's unresponsive.
That sends a fault report to Microsoft after which Workstation can be restarted.
The Suspend operation presumably succeeds because after restarting Workstation the VM can be resumed.
But preventing access to all other running VMs is a really big bug :-(
15.5.6 build-16341506 on Windows 2004