Window opacity bug
 

Three times now I've had the opacity of all the windows suddenly go from clear to black. When this happens they won't change back to clear and the windows on all my other toons are the same. Changing the opacity controls does nothing & each time I've had to uninstall Thor & reinstall, which is a PITA because then I have to set up each toon again.
Any suggestions?

My guess would be that you have a corrupt window placement file (server_character_eq2_uisettings.ini).

I'd try wiping the existing one and making a new one (either via the window wizard in the auto updater or logging in and letting the game make one then manually reposition the windows).