Had another person recently with the same (or similar problem). He reloaded his drivers for his graphics card and that wall turned into brick (with the keyhole plainly showing).
Here are the two threads:
http://www.ironworksforum.com/ubb/cg...c&f=4&t=006646
http://www.ironworksforum.com/ubb/cg...c&f=4&t=006653
Let us know if it worked for you. Good luck.