Comment 12 for bug 983291

The best workaround I have found is to 'keep current settings' when the timed dialog appears (in display settings). Once the settings are applied, although the display is rotated 90 degrees, I have found that the 'normal' orientation option reappears in the orientation dropdown box. Applying 'normal' then restores the proper orientation, although it has to be reset again every time the second display is connected.

(Dell 630m with Intel graphics. )