I have a 2G 8GB iphone that just went nuts for no reason....when i plugged into my PC a popup was displayed saying "usb not recognized" and the iphone would not sync or charge. After a week of messing about with cables other peoples PC's and reading other peoples trials and errors about logic board failures and take it back to apple and apple blaming vista's drivers this is what i did...
1) Deleted Itunes,Quicktime,Safari,MobileMe,Apple software updater, Apple mobile device, any driver files called usbaapl.sys and anything else Apple related.
2) When all Apple related stuff was deleted i plugged the iphone into usb port and windows recognized it as iphone and installed Windows drivers. When driver install was complete iphone was recognized in device manager as Imaging Device and green charging icon was displayed on iphone screen.
3)I left iphone plugged in and reinstalled itunes, Happy Days itunes installed and when it was finished iphone was recognized in itunes and charging battery was displayed on screen!!!
4)Restored iphone to version 3.0 and jailbroke and unlocked using Redsn0w 7.1...
I did this on Windows Xp system but hopefully taking these steps on any PC will sort your problems and if at 1st you don't succeed try again,i was trying for a week hope this helps.GOOD LUCK
