I had that problem too. Luckily, after hours of googling, i found someone in symbianfreak's forum who have the same issue.

Seems like a problem with the cable drivers after updating to the latest NSU.
So, the solution is to uninstall latest NSU (though i myself uninstalled everything), and install the old version that came with the CD.
Run Nemesis. Should be able to detect your phone now.

It's tedious to change back your code though... lol.

Talking bout barcodes, seems like Barcode Reader (that came with N82) also got an update.
Now there's a square to hightlight where it's trying to read, sorta like face detection... cool.