There are several people having the looping patch problem . However you can manually patch the game .
How to manually patch the game
1. get the patch(es) first and foremost doesn`t matter in what order just as long as you have the ones you want or need . all versions of the patches are here http://en.thewitcher.com/patch1-3/
2. disconnect from the internet
3. install the game
4. close the launcher or cd-key registration
5. apply patches in order
6. retry the game
7. reconnect to the internet
8. If you are running less than the 1.3 patch it may be a good ides to run the game from the witcher2exe found in the bin folder of the game directory