Youtube woes, (adobe flashplayer 10 installed) I get a big gray triangle.

I go to YouTube, click on the link to a video, and I get a box with a gray triangle where the video normally is. I get this gray box quite often throughout surfing, and I can normally view whatever the media is after clicking on the box (it's annoying, but I haven't messed with it for the three days I've had this Ubuntu 8.04 hardy hard drive). However, when I click the gray box on a YouTube page, there is a short wait time and then the whole window goes gray (it does that everytime a window stops responding?) and subsequently ceases to respond to anything other than a force quit.
I have Adobe Flashplayer 10 installed. Browser is FF 3.
What am I missing?

Some screenshots:
http://tinypic.com/view.php?pic=2mq3pdj&s=4
http://tinypic.com/view.php?pic=2qa4x2c&s=4
http://tinypic.com/view.php?pic=2qa4x2c&s=4