In profile pages, like ali_fiujnomali, there is a HTML5 element (canvas), but first line of HTML document is: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" ""> that specifies this is a HTML 4.01 document. Please change this line to: <!DOCTYPE html> to tell to Internet Explorer that it is a HTML5 document.
You are right but: "_Use a web browser to browse the web!_"
Imho, web page should be valid no matter how browser process invalid ones.