My site is powered by Joomla 1.0 (russian translation and some custom modules)
Maybe the problem is in Joomla URL generation?

It always replaces ampersand sign in URL with & code, for instance:


http://www.licey1547.msm.ru/index.php?option=com_content&task=view&id=293&Itemid=53

but no other software considers it a malformed URL

Does avast have any log file, where I can find more details about what it considered “mailformed URL”?
(I’m already tired trying to guess what is wrong with my site ???)