When I try to watch a video on Youtube I get this message:
Hello, you either have JavaScript turned off or an old version of Macromedia’s Flash Player. Get the latest flash player.
What am I doing wrong? How do I turn JavaScript on? Did Macromedia’s Flash Player recently change?
They’re constantly releasing new versions of Flash. Adobe is up
to version 9 of its flash player, now.
If you go to this page, and you have JavaScript enabled, it will tell
you what version of Flash you have installed. That should narrow
down your problem to JavaScript or Flash.
Thanks. That site says I have Flash 6.
So how do I uninstall Flash 6?
The queer thing is that YouTube works in Firefox (which I’ll use if I have to), but not IE (my favorite). 
Today it is randomly working. LOL!
I had this same problem, everything was up to date but it didn’t work. I would recommend going to this webpage. Scroll down until you get to the part I have quoted. It takes a while to get down there. Then, follow the links they have in the instructions for removing and re-installing the flashplayer and do just exactly what they say. It solved my problem. I have no idea why but maybe it will help you too. I didn’t have to go to the “Trouble with Windows” part, it was very simple. Good luck.
http://www.adobe.com/cfusion/knowledgebase/index.cfm?id=tn_15511#fixall
Try this first: How to fix almost all Flash Player issues
A version of Adobe Flash Player is pre-installed with most popular Internet browsers. Sometimes, problems with a Flash Player that’s already installed can prevent you from upgrading to the latest player. You can resolve almost all difficulties by taking the following steps:Check System Requirements to ensure your configuration is supported.
Make sure you have the latest version of your Internet browser. Installing a new browser can often repair issues with browser installations, and newer browsers may also offer improved security.
Remove Flash Player (see How to remove Flash Player from your computer above).
Restart your computer.
Download and install the Flash Player from the Flash Player Download Center.
If you still have problems, move on to Trouble with Windows Installation or Trouble with Macintosh Installation.
Oh, sorry, I didn’t see that you actually do have an old version of Flash. Then it should be simple enough just to install the up-to-date one. Go to the website, they will worry about uninstalling the old version. If I am understanding the problem correctly.
http://www.adobe.com/products/flashplayer/
No, some older versions of Flash, or browser+Flash combinations, won’t uninstall the older version of Flash correctly. That’s why Adobe is recommending you uninstall the old version of Flash manually, reboot, then load and install the new version of Flash. I went through this, trying to get rid of Flash 6 so I could load Flash 9.
djm
Hey, I bet that was my problem. I just assumed they dealt with it. Good thing you said something!
Thanks people. You’re all so brilliant. That’s why I love you. (And because you’re beautiful.)
I’m not. Maybe Cynth is. Probably. 
djm