Page not found (error 404)

The page http://cpiact1.altervista.org/moodle-2.5.5/calendar/set.php?return=aHR0cDovL2NwaWFjdDEuYWx0ZXJ2aXN0YS5vcmcvbW9vZGxlLTIuNS41L2NhbGVuZGFyL3ZpZXcucGhwP3ZpZXc9bW9udGgmY2FsX2Q9MSZjYWxfbT00JmNhbF95PTIwMTcmY291cnNlPTE%3D&sesskey=mcy24h3fJy&var=showglobal was not found on this server.

This can be due to:

Pay attetion to UPPER and LOWER cases
http://site.altervista.org/Page.html is different from http://site.altervista.org/page.html