Page won't load on IE9 unless developer tools are started first

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http://serverfault.com – One of my pages (with very extensive javascript) won't load on IE9. It loads ok in Mozilla, Chrome, Safari and Opera. If IE9 Developer tools are running it loads fine. If I load IE9, load the developer tools (F12) then kill the developer tools it still loads fine. If developer tools are running then sometimes (but not always) the first message in the console is: HTML1113: Document mode restart from Quirks to IE9 Standards Doctype is: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www (HowTos)