When I connect my Galaxy SI900 with the PC, I get the message, "A USB device connected cannot be recognised". I reinstalled drivers on the PC and it resintalled Kies. Thses didn't resolve the problem. Any suggestions.
I was having the same issue with Kies. Latest version of Kies and latest USB drivers solved my issue.
Sometimes a damaged usb cable, low quality cable, or one that's too long can cause this as well. So perhaps make sure you're using the original cable that came with the device. Also if you're using a usb hub with a desktop computer try plugging the cable directly into the computer instead.