I've been getting this problem lately:
When trying to start a VM, VMware Player just sits there, doing nothing; the VM does not boot.
Trying to close the VMware Player window brings up the error message "The virtual machine is busy" - this error message can not be closed.
Task Manager shows the vmplayer.exe process is using as much CPU as it can get, and the vmware-vmx process has not started.
Killing the vmplayer process closes the windows, but does not solve the problem - trying to start the VM again has the same result as above.
Killing both vmplayer and vmware-usbarbitrator64 does help, although the VM seems to boot slower than usual.
Host is Windows 7 Ultimate 64bit
Guest is Windows XP Professional SP3
Player version is 5.0.1 build-894247