Sweetfoo, searching our forum for "unauthed" finds a few reports of this.
Of those that were troubleshot to completion, there were other non-ULib errors occurring before the ULib loaded, and basically, though we haven't seen what is causing it, some addon is breaking the player spawn hook that many addons use, including ulx to authenticate on join.
I noticed in one of your errors bans.lua is mentioned, and in another, way down the trace, net.lua is mentioned; you wouldn't happen to be using URM by any chance?
If so, try removing it and see if that helps. The author of URM had to update recently due to a conflict when bans load. If you're using it, make sure you go to the author's release thread and get the latest.