Does installing a previous version on a clean profile help?
Had the same problem with error 15.
See if you have a program called “sendori” installed. I uninstalled it and wiped all traces of it with revo uninstaller. Then I reinstalled dragon and everything works fine.
Sendori is some kind of malacious software directing you to specific sites. Seems like it interferes with dragon.
Hope that works for you 
here is fix I spent all night trying to see if it was maybe a malware, my Kaspersky did not want to comminucate. but after update all went to kaput. I tried this and it worked
type cmd in search
will take you to new window
type netsh int ip reset reset.log press enter
then type netsh winsock reset catalog press enter then restart your computer
Hope this helps worked for me! ;D
Thank you for giving a clue as to what has been preventing Comodo Dragon from connecting to the Internet. I uninstalled sendori and lo and behold Comodo Dragon is connecting to the Internet again. :a0