Q: iTunes 11.0.1 sync problem in step 2

last saturday I bought an iPod Touch and downloaded an iTunes here at my windows PC.

syncing is not a problem at that time and all the apps that i downloaded is syncing into my iTouch very well without any problem

then suddenly yesterday when i downloaded some apps for my iPod then i tried to sync it, a pop out message suddenly appear saying that the itunes encountered a problem and needs to close.

i re open the itunes because it crashed and every time i try to sync it always happen.

my itunes says that it is the latest version.

i've already tried unistalling the itunes in my PC then installing it again and downloading again the itunes.

i noticed that when i try to sync the steps show above the itunes with the candybar loading screen, when it comes to step 2 which is "backing up" after it loads the message always pops out and crashes the itunes. and this annoys me very much.

btw conneting to my PC via cable wire/usb wire.

PLEASE I NEED A HELP FOR THIS! THANK YOU!!