I get this on IE 9 following what the OP said to do to reproduce the problem in Console
[CODE]SCRIPT438: Object doesn't support property or method 'count'
xenforo.js?_v=170916bd, line 2115 character 4
SCRIPT438: Object doesn't support property or method 'count'
xenforo.js?_v=170916bd, line 2115 character 4
SCRIPT438: Object doesn't support property or method 'count'
xenforo.js?_v=170916bd, line 2115 character 4
SEC7113: CSS was ignored due to mime type mismatch
?_v=170916bd
XenForo.init() 2ms. jQuery 1.4.4, 1.2.5
SCRIPT438: Object doesn't support property or method 'count'
xenforo.js?_v=170916bd, line 2115 character 4
SCRIPT438: Object doesn't support property or method 'count'
xenforo.js?_v=170916bd, line 2115 character 4
SCRIPT438: Object doesn't support property or method 'count'
xenforo.js?_v=170916bd, line 2115 character 4
SCRIPT438: Object doesn't support property or method 'count'
xenforo.js?_v=170916bd, line 2115 character 4
SCRIPT438: Object doesn't support property or method 'count'
xenforo.js?_v=170916bd, line 2115 character 4
[/CODE]