In some Windows versions when starting GiD it could appear a message like
'There is no disk in the drive. Please insert a disk into drive' for some units.
It happen only is GiD was not registered with a password and try to find it in all units, then only asking for the unit could raise the unwanted message box.
A way to avoid this window is to change a setting on Windows: to do it start regedit.exe and modify the key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Windows\ErrorMode
changing its value=0 by 2