randomly layout stopped working properly

hey everyone, my blog http://webpl.us (i’m creating a new theme for it) started acting strange the other day. I posted a typical post and then bam all of a suddent the layout dropped the menu below everything. now i reverted to the default layout, and its still doing it.

i exported the entries to a new copy of wordpress, and its also giving me the error. any ideas? i use the rich text editor in wp to post, try to avoid posting my own html in there since it seems to cut everything out anyway.

other note. how can i get wp to allow me to embed youtube and other videos in the page?