You are not the only one...I have the same problem as with others that have been reported on other forums. IT9 seems to break 3rd party USB connections. IT9 must be overwriting one of the files for connecting via USB. BTW, I am running WIN 7.
I went back to iTunes 8.2, but you will lose your playlists and such...IT9 overwrites this file (iTunes Library.itl and possibly others located in your C:\Users\*YOUR USERNAME*\Music\iTunes) and CAN NOT be read by 8.2 after upgrading...