[Blackberrydoc]

I tried all the above,
install/unistall.
Reboot, new cables.
Nothing worked.

Until I noted that where the usb cable, short end entered the blackberry, that the connection seemed loose.
I took some pliers and gently squeezed the connector end on the usb cable that inserts into the blackberry to creat a more snug fit (so the "female end on the cable was pressed in slightly to make a better attachment with the male end found within the blackberry) and finally resolved the issue.

The device was finally recognized and syncs were successful.

It appeared the problem was that the part within the blackberry somehow did not seem to get a snug fit. Rather than manipulate the blackberry, I found that gently creating a tighter fit on the usb cable at the small end that attaches to the blackberry (not the larger one to the computer) that the problem of not recognizing the device was resolved.
Hope this helps you.
blackberrydoc