This is a DLL error. One or some of the game's DLL files have been corrupted or are missing.
If you have a disk, you can try simply uninstalling and reinstalling.
If using Steam. Go to your Library in Steam, scroll down and find Witcher 2. Right click on it and select properties. In the window that pops up go to Local Files and once there select Verify Integrity of Game Cache. Once done try running the game again.
The next thing to try is to run Windows Update. Go to your Start Menu, select All Programs and Scroll down to Windows update and run it.
If that didn't work then the next thing to try would be to uninstall the game completely and run a registry fixer. If using Steam, follow the above steps, only instead of Verifying the Integrity select Delete Local Game Content instead. Backup your save files if you want, you don't need to be rid of them. Otherwise take everything out. If not on Steam, just use the uninstaller that's included with the game in the game's folder.
Next, download and run CCleaner from here:
CCleaner - CNET Download.com [Don't worry, there is a paid 'Pro' version, but you only need the free one.]
Once you have that installed run 'registry cleaner' in the registry tab.
Restart your computer.
Once it's back up, reinstall Witcher 2. If using Steam, you'll have to redownload the game. There really is no other way to fix this issue.
