Conditional Logic Problems IE9 with signature field

Conditional logic that is working on FF, Chrome, Safari etc is breaking on IE9. I am using GF 1.6.4.4 with WP 3.3.2

My form has the signature field. When I remove the signature field the conditional logic starts working just fine all of a sudden on IE9. I get the same issue even with 2010 theme, other plugins disabled and with noconflict mode set.

Poking around with IE developer console I do see some js errors. The same errors are apparent on other browsers but don't seem to cause any damage to the form. I think these errors may be terminal for my forms logic on IE

My form has quite a lot of conditional logic and some hooks and pre-population so I have a simple one here http://bit.ly/KcgjD5 where you should see the errors on a console (after proceeding to page 2). The basic conditional logic on this form is still working but you will see the js errors.

SCRIPT438: Object doesn't support property or method 'chosen'
ss.js?ver=1.0.beta1, line 8 character 12790

and

SCRIPT438: Object doesn't support property or method 'chosen'
gravityforms.js?ver=1.6.4.4, line 655 character 13

Removing the signature field results in no js errors and my complex conditional logic working fine on IE9.