[CentOS] GUI Question

Hi,

There's something weird happening to my CentOS VMs, cannot switch back to GUI. Black screen with a single underscore character at top left of the screen.

Ok so I have ESXI 5.1 host, with 3 VM all running CentOS. I rebooted the esxi host yesterday for a power maintenance. All went well... until I switched console on the vms.

I was able to login using the GUI, then I pressed Alt F5, then I was sent to the text console... I usually do this to save energy. I did the same for all the Centos vm... now I wanted to switch back to GUI but I can't. I even pressed all the keys from F1 to F12 but were not able to get back to the GUI for all the VMs.

Can you please advise where Im missing?

Regards, Deno