MBP resolution stretched and over-scan on external display

Question

Hey all, I started playing Portal 2 on my MBP, at a resolution of 1280x800--the game killed that resolution on my external forever since.
When I ran the game for the first time it appeared stretched on my 16:10 external monitor (Samsung SyncMaster 275t plus). In the game settings the resolution was initially set to 1024x768 and the aspect ratio to 4:3. When i corrected the aspect ratio and resolution everything went well until I exited the game. From that point on, whenever i run that monitor at 1280x800 from the MBP it is  stretched, over-scanned and ill positioned. Ever since initially running Portal 2 the external monitor has detected the resolution 1280x800 as 1024x768, but it is still able to detect and run other resolutions correctly.
I've tested the laptop with other external monitors at 1280x800 and it's able to drive them without issue.
I've tried...
...to reverse the steps to fix the problem, but haven't had any luck.
...to reset the monitor, through the OSD, holding the source button, and just plain unplugging it for a while.
...resetting the SMC and NVRam
...using 3rd party software like SwitchResX and DisplayConfigX, but neither of them even really allowed for any relevant options.
...trashing the com.apple.windowserver.plist files in [root]\library\preferences\ and [root]\users\[username]\library\preferences\byhost\
...forcing the EDID using the method described in this forum post (putting a custom DisplayProductID-xxx file in a DisplayVendorID-xxx directory in [root]\system\library\displays\overrides\) http://www.insanelymac.com/forum/index.php?showtopic=208410
...modifying the standard timings and detailed timing blocks of the proper EDID and swapping it with the file from the last thing that I tried.
I am well and truly out of ideas. Your help is greatly appreciated.

Answer 1

no suggestions?