Video Problems

[mr_pikachu]

Okay, so I got a new computer recently. Good times. For whatever reason, though, I can't play videos on a number of different websites (Youtube's the big one, although there have been numerous others).

On some sites, the video plays for two seconds and then inexplicably pauses; I can jump to another point in the movie if I want, where it will continue. For two seconds. That makes for a very long movie. Certain other videos, though, run fine, aside from a total lack of sound. Also not good.

Some technical discussion threads I've visited say that the new version of Adobe Flash Player is the problem. They recommend downgrading to a previous version or just replacing one of the plugins with an old one. Sounds easy enough, except that this is a new computer. I don't have a previous version of anything. That leaves me at a bit of a loss.

Any advice would be much appreciated.


EDIT: Some technical specs. Not entirely sure what other information would be relevant, so just ask.

HP Pavilion dv9700t
OS: Windows Vista (64-bit)
Browsers: Mozilla Firefox 3, Internet Explorer 7, Internet Explorer 7 (64-bit mode)