We are currently using Creo 8.0.2.0, and when I double-click on a dimension to enter or edit the value, the prompt comes up and then immediately disappears (see attached images). I have less than one second to try and enter a new value.
I'm not having any issues with Creo 8.0.7.0. The white box doesn't go away until I click 'Enter', no matter what I do with the mouse. Are other users at your location having this same issue? Maybe temporarily swap our your mouse and keyboard for different ones and see if that makes any difference.