Comment 4 for bug 856098

It couold not exactly be described as a dialogue. An (apparently empty) nautilus window opened, and the error message appeared superimposed on that window. The interruption appeared immediately before the stage at which you are invited to open a wireless data connection. Dismissing the error message and closing the window allowed installation to proceed normally.

There is a complicating factor, in that the interruption appeared on three separate machines (desktop, laptop and netbook) while I was testing 20110921.2 with a USB stick made with Unetbootin, but can't be reproduced with the (otherwise apparently identical) beta2 release version, which I have been testing with sticks made with USB disk creator.

Sorry to have wasted your time.