Reply to Problems with Traktor pro 2. Need Help

So i just installed traktor 2, it came with my kontrol s2. The first time i open it after i have turned on my computer, it opens fine and runs as it should. However once i close it and then try to reopen it later, it displays an error message saying "could not initialize traktor. Probably another instance is running!" But when i open task manager nothing is running. I have tried re installing the program but still have the same issue. Any help is appreciated. Thankyou