Have a suggestion for you.
Try exporting the NVIDIA driver profile with the Geforce SLI Profile Tool.http://nvidia.custhelp.com/cgi-bin/nvidi...4701918&p_olh=0
Then open the exported file and look for the proper profile entry (Assuming you created one for the game).
Once you located it look for a specific entry under the profile named: Setting ID_0x00d55f7d
That is the specific entry for Antialiasing Compatability, if it is not there that means NVIDIA Inspector did not properly register it in the profile.
In that case manually enter in that line under the game profile and add the specific antialiasing compatability string from Oblivion(0x200100c5) or S.T.A.L.K.E.R(0x0000f0c1)
It should then look something like this: Setting ID_0x00d55f7d = 0x200100c5
You might have to enter: UserSpecified=true at the end of the line as well so it would ultimately look something like this: Setting ID_0x00d55f7d = 0x200100c5 UserSpecified=true
Then import the new profile using the same tool.
Make sure override is selected under antialiasing mode in control panel or NVIDIA Inspector and see if that works.
Was messing around with the NVIDIA Inspector tool and noticed that it didn't always save the new antialiasing compatability setting when I hit apply. It did save other settings that I tried but not always that one. Sometimes I had to hit apply button more than once for the setting to register.
Was able to confirm all this by using the Geforce SLI Profile Tool.
Hope it works for you!