Same problem. Have tried numerous devolutions down to resetting the slingbox ... online password stored in profile still conflicts. Deleted box from online directory to no avail. Apparently Sling has decided to disable older boxes in an attempt to get us to purchase newer boxes ... what they've succeeding in doing is motivating me to find an alternative to their products.
I had the same problem with an HD Pro after resetting it.
No matter what I did it would not except any password.
I downloaded Slingplayer for PC and this allowed me to input an Admin password and now my HD Pro is up and running.
I would suggest you download Slingplayer for PC and try to reset your Slingplayer using this app.
My slingbox keeps asking me for an admin password after reseting. I have already tried using "admin" as a password but this does not work. I have also done this on several different browsers (safari, firefox) but this does not work. I finally tried it on two different laptops (both macs) which neither is running antivirus/firewall software but this does not work. Is there anything left for me to do to try and fix this?