Firefox youtube an error has occur, please try again later?

[Alice]

My friend just built a new computer for me and when ever i go on firefox and go on youtube to watch a music video, it plays for the first 3 seconds and then it automatically switch to 1080p and then it said an an error has occur, please try again later, i refresh the page and occur with same results. I tried a different video that isn't HD or anything and it just play for 3 second and it shows and message saying an error has occur, please try again later. So i tried going on youtube on chrome and it doesn't happen, it plays videos all the way to the end. The flash player is the latest version as my friend installed it from adobe's website. I am running windows 7 btw. Can anyone help me solve this? if so that would be great! Thanks!!
@ankit, i've tried that and i've tried clearing out the cache, cookies and history and everything else.
I'd try going to a different website and watched a drama and it requires flash and it doesn't happen like this. Does anyone know whats the problem?

[Ankit]

You can try this, may be if it works.

Press Control + Shift + Delete keys all together, a pop up window will appear to ask to delete all cookies and things. (Select all check boxes delete everything and restart Firefox).

Hope it works

[Sum Ting Wong]

http://tinyurl.com/79ddfwh