Odd. I have a Canon 5200F. Some time ago I updated the drivers from the Canon site and it would not work anymore. I reinstalled the older drivers and all was well.
When I upgraded to Vista the scanner worked fine for several days but then stopped. Nothing obvious in device manager so I unplugged the USB connection, uninstalled the drivers in Device Manager and plugged the scanner back in again, the hardware wizard found the new device and I was away again.