YouTube codes goes weird in WordPress2

I’ve used youtube before on wordpress1.5 and it works fine and everything, even when i upgrade to wordpress2, the previous youtube embedded in my blog is still working fine.

Except for now everytime i paste the embemded codes , the whole blog breaks apart like some crazy html coding went wrong and when i edit the post it seems that the embedded file codes are somehow screwed up.. anybody know how to rectify this? thanks in advance