I too like many of you have had the same problem with my S2 not connecting with kies and ive tried everything that everyone has suggested on this thread from enabling usb debugging mode, to enabling usb debugging mode and disenabling it right after, tried taking both sim and usb out, tried installing windows media player 11, tried the #7284# dial tone procedure (when i dial the number it simply says "connection problem or invalid MMI code"), tried simply turning phone on and off.
however i tried the one method of going into setting>wireless & network> usb utilities and putting it in usb mass storage mode and the drivers run (the little popup that hardware wizard has found your device) but then it prompts me with a message saying
"Reconnect device in Samsung kies (Pc Studio) mode. current connection mode not supported by kies. Check usb setting-> applications-> development-> usb debugging (x))"
i will follow exactly in these instructions and usually the drivers connect just as before but i get the exact same message prompt even though I just did it....it confuses the hell out of me and i dont know what to do! im about to throw my phone out the window! can some please help me with this ive practically tried all of the previous methods and nothing has worked!