Right click on a file in Firefox

When I'm using a Firefox and do a right click on a file (attached to a node), Firefox wants to save the file with a strange filename (ex. " http _adres.strony.edu.pl_podstrona_ q=system_files_tytul_2.txt.htm ") and 'htm' extension. The same thing (right click) under Internet Explorer and everything is fine - good extension and good filename (ex. "tytul.txt"). What is going on? How can I repair it ?