I'm having a problem with my DNN 4.0.x. Many of my "tabs" have disappeared, along with a bunch of my users. An inspection of the database confirms that all the missing stuff is still there, but it won't show up in the DNN. I can log in with all the "missing" users (even though if I try to view all users, I only see the superusers), but even users that are admins don't get the "Admin" tab. When logged in with a host superuser, the Host tab is there. When logged in, I can click on "Site" in the common tasks on the dashboard, but it just takes me to the home page.

No errors are being generated, so I can't provide much more than that. I've restarted IIS and SQL Server, but the "disappeared" tabs and users don't come back. Help!

Nothing I know of has changed.

I did fix it the first time, but I can't remember what I did (I may have just rebooted the server).

It's happened again now, and again as far as I know nothing on the site has changed since yesterday when everything worked fine.

Edit: I've rebooted the server, and now MORE tabs are missing. I'm frankly baffled.

Second edit: I logged in as the host account, went to skins and tried changing the portal skin. When I tried to "apply" it, it didn't actually change the skin, but all the tabs came back.

Anyone have any idea why this might be happening?