It says 'Incompatible menu file (containermenu.swf)', and after I press enter/continue, it says the same thing but 'SkyUI/itemcard.swf', and then 'SkyUI/inventorylists.swf', and finally 'SkyUI/bottombar.swf'.
So I get these error code 5's every time I try to loot something, pickpocket someone, buy/sell something or open the favorite menu.