Sheridan City Circle just poped up.  
I got in there and was on the last step of checking out when I got this error:

Sorry...The operation you requested did not complete in a timely manner.  
Please try again or contact Passkey SupportThank you for your patience. 
The Passkey GroupMax Team

 Is this something wrong with my computer or is that just what it shows when the room is gone?

Does it keep happening?

Sounds like you had the room snatched from you while you were filling things out. 

Yeah, it has happened a few times over the last several weeks.

That's what I figured it was... but I thought a room got 'held' when it was put into a cart.
Wanted to be sure it wasn't a computer setting or something I could control.