Can't see any issues raised about this, so thought that I'd ask if anyone else has seen this.
I find that, when Start 11 is running, there is often a horizontal strip down at the bottom of the screen that does not respond to mouse clicks. For example, in my email client (emClient), the Email, Calendar, Contacts, Tasks buttons are down at the bottom on the left and often, they do not respond to mouse clicks. The taskbar works fine, but not other apps. Once I disable Start 11, they all work fine again.
For the moment, I have had to disable Start 11 permanently.