There is a glitch with the shields that happens about 60% of the time, when the shield gets broken it doesn't disappear it remains in the inventory with negative durability. You can't attach the shield(of course), but you can't drop it either.

Also there is a problem with the indestructible shields, such as the lightning shield.

Here is a list of the enemies that broke the shield and the attacks that broke it.
Orc: Normal Weapon Attack, power attack
Necromancers: Fire Attack
Vampire knights: Normal Attack, power attack

It then either disappears from inventory or gets stuck in inventory like the other shields, the difference is that you can't equip it anymore.

Hope that information helps fix the bug.

Same here sometimes when I Enemy Hit my Shield it drops to the Floor, I pick it up, Its in the Inventory but I Cant use It any more !! There are Some strange Sings by the Requierements.This happend whit the Lighting Shield. DAMM, I cant belive it in V 1.01 there was this Headlink error, in V 1.02 the Replayced this one Into a bug Whit the Shield. Again I cant play the game to the End. So, What the Hell, did someone Humankind tested this Patch ? Hope there is a posability in the Future to Play this Game...

Did we ever recieve a response to this problem? I am having this problem as well and would like a solution.