This question seems to come up quite often. You run the CUI command and it appears to execute, but the dialog box never appears and AutoCAD appears to be hung. If you hit Escape the command line once again accepts input but you never saw the CUI dialog box.
The cause is likely that the CUI dialog somehow came up offscreen. This happens most often in systems with multiple monitors or laptops that connect to a secondary monitor.
The solution is rather simple.
- Run the CUI command
- Type Alt+Spacebar
- Note what side of the monitor on which the shortcut menu displays
- Select Move from the shortcut menu
- Press the opposite arrow button until the dialog box appears, e.g. if the menu came up on the right side of the monitor, use the left arrow button