Having suffered the same difficulty with my iPad2, I tried rebooting the iPad2 using the usual way with the slide to power off feature but at the same time I pushed the button at the bottom of the iPad2 that takes me back to my home screen or that if pushed twice will show the running apps.
The iPad2 rebooted (I had to push in the off/on button again during what appeared to be rebooting because the white Apple seemed to stay on).
After that, I was able immediately to synch like before, although trying to access Pages documents is still not working (that is, what I see on the iPad2 in Pages is different from what I see on iTunes for Pages documents and I can't move them back and forth using DiskAid the way I used to, but document features including moving back and forth seem to work in other apps).
It may be that the two button reboot is what was needed. I haven't yet tried the iTunes music synching, though.