YouTube issues

I looked through some threads and didn't really find anything.... the problem is this: when I go to YouTube and start a long video (like over 4.5 minutes) it will start to get jumpy at about the 4 minute mark and by the 6 minute mark it will stop completely. No errors, it just stops. If I refresh the page and try another video, it will be jumpy right from the start. It's not my laptop, but I did clean over 1gb worth of junk files with CCleaner, but that didn't seem to do anything. Could it be a codec thing? Or just a lack of RAM? Or maybe the available RAM isn't being 'released' after it's used? Any ideas will be greatly appreciated....
Thanks.

 

I forgot to mention.... IE6, WinXP Home SP2

 

Have you tried pausing the vid until it was completely downloaded? I can't see why it could be a codec issue if it initially works. Have you downloaded it to hard drive and tried it that way?

 

No, I haven't really tried much with it... I won't be able to work on it again until Monday, but any ideas between now and then will be appreciated. I'm thinking it's some type of cache issue; the short vids play fine, and longer ones are fine until about the 4 minute mark. Then every vid after a long one gets jumpy too.....