This may be a basic AutoCAD question, but the user is running C3D, so I'll ask it here. He can only open a drawing if its in the previously open files list or he can open with Explorer. If he clicks the open toolbar or selects open from the menu or even types it at the command prompt, nothing happens. It seems to be trying to do something because the command prompt doesn't come back unless he escapes. If he instead hits enter, he gets a message that says it can't find the file specified - even though he never got a chance to specify anything. It's not FILEDIA and he has rebooted. It's also not hiding the open dialog box behind the acad screen. What else could it be?