It could be more serious than drivers.
Are you using the USB cable to connect, or the serial cable connection? My 60CSx started this some time ago, when using the USB cable. Internet research indicated that if it wasn't driver-related (and it wasn't, as the problem existed on multiple computers, both XP and Vista), or a faulty cable (tried several), then it could be that the USB port on the computer had fried the USB port on the unit due to too high output.
I therefore tried using the serial connection instead (NB. you'll possibly need a USB-serial converter cable as well as the regular serial cable if your computer has no serial port), and this was successful, so downloading tracks and uploading routes/POIs etc works. It is very slow, however, and I wouldn't bother trying to upload any Mapsource maps this way, as it would take hours - to upload maps, use a micro-SD card reader instead, as it is much quicker.
I keep meaning to send it back to Garmin to have it investigated properly (and the USB connection fixed), but can live with the serial connection for routes/tracks/POIs now that I've bought the cables (which cost >£25), so haven't got around to it yet.