It happens to me too. It's a pitty. I had to downgrade too. In my case it's a gigabit dlink card.I said some network cards are not working with this version.
I modified the sentence to make it more clear.
https://dl.dropbox.com/u/28541142/supout.rif <- Manualy makedPlease send us support output file from 6.0rc1, when card is not recognized. We will analyze files and try to get cards support back.