Next time you get a black screen, put your VM in maintenance mode in View Admin so it does not refresh if you reboot it.
To collect Agent logs remotely from the Connection Server, run this command in a command prompt
vdmadmin -A -getDCT -outfile file_name.zip -d pool_name -m virtual_machine_name
By default, the vdmadmin utility is located at C:\Program Files\VMware\Vmware View\Server\tools\bin in the Connection Server.
May want to open a case with VMware and have them review the logs
While you black screen VM is in maintenance mode check your event logs App / System / Microsoft-Windows-GroupPolicy/Operational
Search for event id 6005 see what happened before it
What log on scripts do you have for your VDI environment?
Enabling Logon script in GPO Makes Windows Login 10 Minutes Long w/ Black Screen - Spiceworks