MacBook – Image on external monitor is off-center

I have a 13" retina MacBook Pro and an Acer X223W external display, connected via an official Apple Mini DisplayPort > VGA adapter. The Acer is set to 1680×1050 (its default resolution).

I wanted to adjust the colors on the Acer, so as a start I hit the physical Auto button on the display. As soon as I did this, the image on the display jumped over to the left by about 2". So the image is now cut off on the left, leaving a big black gap on the right.

If I switch the resolution to anything else, e.g. 1440×900, it'll fill the display like normal again. But if I switch it back to 1680×1050, it gets shifted over to the left again.

I tried adjusting the horizontal position of the image with the display's on-screen controls, but (a) it was already set to 50/100 (which should be the center), and (b) the maximum value of 100 doesn't move the image far enough to the right to eliminate the gap. So that apparently isn't the issue.

I also tried:

• Restarting/rebooting the laptop
• Turning the external display off and back on
• Unplugging the Mini DisplayPort > VGA adapter and plugging it back in
• Restarting/rebooting with the adapter unplugged, then plugging it back in
• Repairing permissions
• Repairing color profiles
• Using different color profiles (including one downloaded from Acer's website)
• Forcing OS X to detect displays (System Preferences > Displays, hold Option and click the "Detect Displays" button)
• Resetting PRAM
• Plugging the adapter into the laptop's other Thunderbolt port
• Switching the arrangement of the displays
• Changing which display is the primary
• Enabling/disabling mirroring
• Resetting the display via the OSD's built-in reset function
• Hitting the Auto button again

None of those steps made any difference.

Then I tried plugging the adapter into a different MacBook Pro entirely (non-retina 13"). Amazingly, it does the same thing – the image shifts 2" over to the left at 1680×1050.

I'm running OS X Mavericks 10.9.4 on both MacBook Pros if that's of any relevance, but it seems like the issue is with the display itself since everything was perfectly fine until I hit the Auto button.

Furthermore, if I take a screenshot of the external display, it captures the full image. So that suggests the laptop is outputting the image to the display correctly, but the display itself is showing it off-center.

I've found other forum threads that suggest using a different adapter (e.g. DVI instead of VGA), but given that I've always used this display at 1680×1050 with the same adapter, I know it works…

I'm at a loss as to what else I can try to get the image to reposition correctly. Any help appreciated!