There's an issue with Flash that due to a still recent change you find yourself changing it back on a lot of PCs. Here's the phrase you can use at google.com to see what I change first.
-> How do I disable Flash hardware acceleration.
It could be something else but given your details so far, this is what I'd do first.
Ok when I have multiple videos(like at youtube up) sometimes they will all go white with a small gray circle in the middle and exclamation point in the middle of it. I bring up the task manager and delete the internet and the pages reload and work fine. But it happens again for the same reason. I thought it was virtual memory but no help there. Anyone have an idea? Oh I am on a wired internet connection.