I was playing around in the graphics setting and I accidentally changed the display mode from full screen to windows and that's when things started to go wrong. BO2 starts, crashes en restarts in an endless loop. I can't even end it with the taskmanger so the only way out is CTRL>Alt>Del and restart my PC. I tried everything I can think of, verified game cache, reinstalled BO2, reinstalled steam, ran DirectX executables, changed the display resolution form Nvidia control panel and I reinstalled the graphis driver all without any result. Basically BO2 is completely FUBAR.
Then I got an idea and I installed Steam on the C harddrive (I've always had Steam on my E harddrive) to the default location. After that I let steam install BO2 so now that's also on the C harddrive. I started up BO2 and it runs like nothing ever happened. My C drive however is a SSD and I'd like to have BO2 on my 1TB E harddrive (for space reasons) so I deleted BO2 from the E drive and copied over the folder from my C drive to E because I thought if it works on the C drive it has to work on the E drive as well. Guess what, it doesn't. As soon as I start BO2 from E it again gets caught in the same crash>restart loop.
I'm completely out of ideas so if any of you has any clue what's going on I'd love to hear it. Btw, this is on Win 7 64 bit.
Unfortunately, you cannot just copy the folders. It doesn't work at times.
The best method is to delete the Black Ops 2 folder in your E drive. This I believed are due to Windows security and Black Ops 2 setup issues. The folder must be deleted and re-install from Steam.
PS. Even Steam did not delete the BO2 folder, you must delete the folder manually.