after searching for so long i finaly found the answer in curse client support page
http://support.curse.com/home
"Just to let people know; Google broke launching apps from Chrome a few days ago. This means that people are unable to use the "Install via Curse Client" option when downloading...
wow wierd this just started happening to me today aswell, even magnet links were not working (torrent link)
i was able to fix magnet links, but not curse client links
@tarunkumar2 how do you check check the default program associations for chrome?