A thought occurred to me about this ... A couple people have said that it started working for them when they had a new/freshly installed microSD card in their phone. The card that comes pre-installed in the phone has doubletwist on it, including an autorun file. I noticed that until I removed these things from the memory card, Windows was identifying the card as "Media sync powered by doubletwist" or some crap like that. I took all that junk off and it started identifying it as just "Removable Disk." Now, I took off all this before I tried the rooting process, so I don't know if it would've caused any problems. Could it be that this has something to do with it? It doesn't seem likely to me, but I thought I'd mention it.
At any rate, try a new or freshly formatted SD card, see if that helps.