I have the same issue; the first time I try to play with a saved game, as soon as I try to move, my system hangs.
I have an I7-920, mildly overclocked to 330; running Win7-64bit(*GB); Nvidia 295GTX(1GB) with the newest beta drivers. I have uninstalled and reinstalledthe game and used Revo uninstaller to make sure all traces of the game/saved games extra content were all gone. I know my system isn't overheating because after a couple of tries, I can get the game to play for a couple of hours without an issue.
The TW2 configurator automatically configures the game to high; I've lowered to medium and low specs, with the same result; I've changed the resolution to less then widescreen with the same result--when I first start the game it crashes, stops dead and I have to restart.
It's not my Windows install either because a month and half ago, I did a clean Windows install and only have DA2, ME2 and TW2 on my PC.
I ran a dxdiag that came out perfectly fine. I am wondering if it could possibly be my sound card which is an Asus Xonar D2X. Does anyone know if there's an issue with this card? There are no drivers newer then the ones I have. I have googled looking for problems with the soundcard and the game, but haven'y found anything.
I look in event viewer and the faulting application is the witcher launcher. I've tried starting the game from start programs menu; tried running as administrator; tried playing in Win XP compatibility mode.
What has provided the most success is going to the drive where my game is installed (not "C"), opening the launcher from there, disconnecting from the internet, disabling my anti-virus(Avast) and playing the game that way. I can do so for several hours with absolutely no issues. I have to go thru the routine of attempting to play a couple of times, locking up the PC. The third or fourth time, when the game runs okay, I'm good to go.
I've played the game patched and unpatched...it makes no difference. I've played thru the entire prologue once it's working twice with no drops in frame rates, and no crashes. Right now, I'm in the middle of Chapter 1, but the game is just damn bear for me to start and it's a bit disconcerting to have to go thru all this just to get the thing to run. Maybe the next patch will help, but I'm not hopeful.