Thank you for the feedback about 16 vCPU usage.
According to your steps, I don't encounter guest restarting issue. The detailed is as below:
1) Clean Install w2008 R2 x64 Datacenter guest with settings:
-Number of Processors: 1
-Number of cores per processor: 8
2) Keep the guest running, Change 'Number of Processors' from 1 to 2
It is automatically prompted as 'Saving virtual machine state...' and then 'Restoring virtual machine state...'. And the process is completed without rebooting.
Can you please let me know if you have different steps/settings, and attach the vmware.log and WS UI log file? Thanks.
Regards,
Wenjing