Okay this has been driving me crazy long enough.
I have an external monitor who's resolution is 1920×1080 60Hz. My MacbookPro Late/Mid 2010 has been able to work with the monitor and resolution since I've owned it. However, this past month or two the monitor's resolution would seem to reset itself to 800×600.
The reset seems to happen sporadically, usually when coming out of sleep. I also experience the monitor going in and out. I've already replaced the Mini DisplayPort to VGA adapter.
Here's a screenshot when the monitor acts up. I can't get rid of the black vertical borders that magically appear nor can I select 1920×1080 as an option:
Sometimes after several restarts or plugging/unplugging the adapter, the monitor will fix itself. I have no idea what is going on, it is very frustrating.
Best Answer
I forgot about this question, but I eventually did find an answer.
It was a bad cable. The VGA cable was faulty (the Mini DisplayPort adapter was fine actually) - once that was replaced, everything worked fine.