Hello,
I've got a weird problem, just seen on two different 05.03.01 (7) hosts: after calling the "empty recycle bin" function all tabs under Admin are completely deleted from the database! And off course they weren't in the recylce bin.
Navigating the site I get the following error:

An error has occurred.
DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.Security.Permissions.PermissionProvider.CanViewPage(TabInfo objTab) at DotNetNuke.Security.Permissions.TabPermissionController.CanViewPage(TabInfo objTab) at DotNetNuke.Security.Permissions.ModulePermissionController.CanViewModule(ModuleInfo objModule) at DotNetNuke.UI.ControlPanels.ControlPanelBase.GetModulePermission(Int32 PortalID, String FriendlyName) at DotNetNuke.UI.ControlPanels.IconBar.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---

Cannot tell if this is related with the problem on tabpermission (this post), but sure there's a big problem here.
I'm now restoring the db and try to upgrade to 5.4.1 to see if the problem is till there.

Note: both portals on which I got this problem have localization enabled and portal default language set to italian.

 Luiz,
thanks for your answer. I actually used italian language during the first install for these portals, but had no issues til now... and one of these portals is now in production.
Will try to upgrade the one that is not published to 5.4.1, but let me understand: do you mean my user (an host level user) language, the portal default language or what?

Luiz,
both administrators role and admin tab are correctly named, and actually I could successfully upgrade to 5.4.1 setting both portal default language and my user language to en-US. The same upgrade gave me an error when I did not revert to en-US - well.
However, after this successfull upgrade, I off course had to revert my portal default language to italian. And when I tried to click "empty recycle bin" I went back in the tunnel - admin tabs deleted and portal unavailable.

Sure I am disabling this function, but did anybody else had the same issue?

Thanks again,
al.