Many people have issues starting Lotro from a Steam UI. This I have managed to overcome, but now I have a different issue.

It is the shop, or rather any command, as soon as the overlay is active. The game becomes kind of unreachable, no command will make the client react, be it for opening the shop, the inventory, or a logoff. As soon as I close the overlay, the game reacts as usual.

If I look into the overlay log, I see the following:
WARNING: The game hasn't rendered a frame from us in over 10 seconds

Which means, Lotro is actually not communicating with the Steam overlay. What is causing this?
BTW: The machine has an ATI card, but I turned this nasty utility off (and even deinstalled it), that opens an overlay with each Alt+R, so this shouldn't be in the way.

Greetings, Polymachos