[Plugin: Facebook Page Promoter Lightbox] Not showing on IE after Dis-Like

I have a hobby page http://www.studyspanishmedellin.com/

To test the Facebook Page Promoter Lightbox I clicked on “Like” and confirmed that on my second visit there was no lightbox. However after I unclicked the Like on my page the lightbox does not reappear when I use IE, however it works fine and pops up with Firefox.

Of course I have deleted cookies and tried different settings on the Advance tab etc.

http://wordpress.org/extend/plugins/facebook-page-promoter-lightbox/