I see you checked out the article "SlingPlayer repeatedly asks for the Administrator password, even after resetting your Slingbox", did you perform the fifth set down of hard resetting your Slingbox?
If not, have a look at this article below to help you reset your Slingbox:
Once the hard reset is done and the network light comes on solid, go to setup on slingbox.com to set your unit back up again.
Hope this helps!!!
Sling Media Moderation Team