Okay, I have found a way to fix it, although be warned it is a bit of a hassle and imo, not really worth it unless you really REALLY want the launcher.
What I did was a clean reinstall of TW2, completely erasing any sign that the program had ever been installed (I did this by completely reinstalling Windows, but I am assured that there are ways to do that without going quite that far)
I applied the patches and voila! the launcher was fine.
Right up until I opened it while I was connected to the interwebs again, when it stopped started doing the same thing again.
So:
Step 1: Uninstall TW2 thoroughly
Step 2: Reinstall TW2
Step 3: Apply patches offline
Step 3: Do not open the launcher while connected to the internet.