Heisenbug in IE9 - main page doesn't load properly unless Developer Console is open.

In IE9 when I load the page initially the left hand feed list doens’t open.

But then when I open the Developer Tools to get any error messages, the page starts to load with no problems.

The only apparent error in the log is:

LOG: / UI Layout Callback Error
The west onresize_end callback is not a valid function.

(PS: http://en.wikipedia.org/wiki/Heisenbug)