I'm not sure what is going on, if it's the results of a massive memory leak, but every once in awhile when I quit playing Witcher it doesn't release completely. I'll quit, but it still looks like it's running in Steam, and I can still hear the menu music playing and see the icon down in my taskbar.

The worse part of this is it also kills my Windows performance. I've tried opening the task manager, but it takes forever to open, then I get Windows messages saying Windows has stopped responding. Crtl Alt Delete doesn't respond. My only option is to kill the power and reboot the pc.

Could this be a memory leak?

You have page files enabled? If not, please do enable them.

this happened to me for the first time today as well and am suspecting patch 1.6 as the culprit as i have been playing seamlessly since release date

No trouble here. Playing the fresh TW3 with the patch. You sure your page file is on?

Me too last night - I'm on Galaxy now, so it's fully patched.

On occasion in the past it's quit out, and the music has played for a further 5 seconds then stopped - even when running "pre-Galaxy". Last night though, it quit to desktop but was clearly still running in the background as a review of the Task Manager still showed it holding on to >2gig of ram (when the task manager finally came up).

I think page files are a red herring here to be honest.