I and other people were pestered last night and this morning by an Avira antivirus popup that was very badly-behaved.
This survey popup wouldn't go away when told to.
People found that clicking in reply would leave a "this link is broken" message, and the shape of the box would stay on top of everything else. Killing ipmgui.exe in Task Manager would solve the problem... until the popup returned around 90 minutes later!
However, just as I complained on their forum, Avira posted their solution to the problem:
Avira ignore complaints or feedback quite often, but on this occasion they responded pretty swiftly.