My ISP’s DNS servers cannot resolve any google.com or google.ca domain names. Other domain names, such as bing.com and yahoo.com (hmmm, what a coincidence) resolve just fine.
For now I’ll be using OpenDNS servers: 208.67.222.222 and 208.67.220.220. I made the change on our router.
Of course, most people would assume that it’s google that’s slow or broken, but you can tell it’s not the case because the browser gets stuck at “resolving google.ca…” Once I changed the DNS server settings, everything is back to normal. This has been a recurring problem (off and on), but it’s always targeting google to the exclusion of all other domain names that I know of. But it’s a purely coincidental coincidence that frequently happens by coincidental chance.
Eventually, some other unfortunate and totally unintentional glitch may block traffic to google altogether, so we may have to change ISP or use our ISP’s preferred search partner.  Perhaps another glitch will also totally block my VOIP provider; our ISP would be more than happy to benevolently help us by signing us up for their phone service (only thrice the price we currently pay!)