Seems this has been going on a while - before the upgrade. Can you think of anything else that was changed on your system around the time you started experiencing this problem? Did AOL release an upgrade that you installed? Did you install a pop up blocker? Did AOL install a pop up blocker? When you say you click on links and get the ol "Page cannot be found" error, that makes me wonder if a pop up blocker is preventing a new browser window from opening (either nothing happens or you get that error when clicking on a pop up link). That would explain why sometimes you can get in and other times you can't - depending on if you already have a browser window open. If you are trying to open from a favorites bookmark, you already have a window open and the new one may be getting blocked.
If you are using a pop up blocker, you should be able to set in the options to allow all pop ups from the SOG site, or add
http://forum.portraitartist.com to the pop up blocker's Allow List. Either that, or you can temporarily disable it while visiting SOG.
If that is not the problem, I am stumped.