There is a bug in jquery.bgiframe of versions before 2.1.2. The bug occurs in IE9 on Win7. The cause is slightly incorrect regex pattern to test with a user agent string which indicates that this is IE6. The pattern looks only for occurrence of ‘6.0’. But this is misleading because IE9 browsers may have 6.0 sub-string for some other features of their system.
The correct version of the plugin starts from 2.1.2. The pattern was changed there to ‘msie 6.0’. And that is more accurate mark.