The following solution courtesy of dsogaming.
First of all, you will need Nvidia’s Inspector Tool. After installing it, run it ,click on the configuration icon next to the ‘Driver Version’ and browse until you find the one for Skyrim. Now select Skyrim’s profile, scroll down and choose the ‘Ambient Occlusion’ setting. After that, type this compatibility bit – 0×00000003 – in the ‘Ambient Occlusion usage’ option and you’re done. Apply the changes, close the program and you are good to go.
source: http://crashfixes.com/fixing-skyrim-crashes-freezes-errors-steam-crash-no-sound-lags-choppy-framerates/2/
OK my Q ...possible with ATI card users ?
