Windows 8.1 pro, ie11 with no add-ins enabled other than Shockwave Flashplayer and Avast browser add-in.
If I try to log into a Flash-based web page only the top inch or so of the window is displayed.
If I use a different browser it works fine.
If I disable the Avast add-in, but enable all other add-ins, then it also works fine.
Just thought that you might want to know.
The offending web page is
http://www.bridgebase.com/client/client.php
arrived it by going to
http://www.bridgebase.com
and then click on “play”