Siketa asks:
Has anyone experienced same behavior?
Yes. I have reported about this for my updates to versions 17.x. I am still on version 17.5 of CD.
Worth noting: Windows XP, s.p. 3, 2.0 GHz processor, 512 MB RAM, 17 GB free disc capacity. Extensions currently present and enabled: Adblock, W.O.T., craigslist.pop.
Note also: My installation is set to open in Incognito mode. I state this in case it has meaning for updating Comodo Dragon browser, since I do not remember if I ever mentioned this in regard to my update attempts in my update failure reports.