So iv'e recently just updated my firmware to JM2 yesterday, unfortunately my phone wouldn't sync with kies so i updated it directly through odin. Everything is going good my phone is allot faster, no black screen (for now), no lags so far so good exept for the fact that whenever i go to the android market and download an app it gives me download unsuccessful and it would cancel my download..... I would really appreciate if someone would be able to help me.. Should i flash another firmware? and if so, witch one ?

I had this problem too and had to reflash and factory wipe. I also pointed Odin to all 4 files unlike what it says in tutorials I read. Ie, the correct pit file, code file, phone (modem) file and csc.

One more thing. When I first got that problem at one point Android store complained my phone was missing an ID. I had noticed when doing a *#1234# that only pda had a version in it so I decided to give what I did a try and it worked