Flash Player/Graphics Problems

I have recently started having three problems that I assume are related because they started about the same time and seem like they could result from a common cause. They are: 1) Any web site that requires Flash Player tells me that I have to have it to use the web site. I have it, and I have even tried removing it and reinstalling, but web sites can’t tell it is installed on my computer. 2) The Dell Support pop-up keeps coming up with the same messages even after I read them and/or click the box not to show that message again. 3) On some web pages where there is supposed to be a picture I get the little rectangle with a red square, green circle, and a blue triangle instead. This seems to be web site specific. Any idea what the problem is?  Thanks, Jim