I was opening zoom and my imac hung up, and I force quit. Had to restart computer. Since then, on both chrome and safari, gmail and yahoo mail don't work. The mail boxes opens, but I get a spinning wheel, and eventually have to force quit. Google photos works, but not google maps. Some other sites work, some do not. I disabled my antivirus and ad blocker, to no avail. I have another imac running sierra connected to the same server, and this one has no problems. Help please.