Hi there,
after months of research I managed to install KNIME 2.7.2 32 bit on w7 in presence of AVIRA PREMIUM ..... ;-)
People have to check the default settings in expert mode and thick few checkboxes in
Internet Protection>Web Protection>Scan>Exception
Here, as default, only and video files are thicked as exceptions. You have to thick also Archives (zip, jar etc.), documets (pdf,doc) and executables(exe) otherwise connection to knime,org will never be allowed and no update will happen. Interestingly enough, normal download of knime installer from knime download page is not affected by default settings.
Hope this will help AVIRA users to save time!
Best