Adsense Ads not Shown on Firefox but on Others Browsers Work Fine

For the last one month on my site adsense ads not shown on Firefox. Solid Color is showing instead of Ads. I set in Adsense Ads Backup option "Solid Color" if ads not available. But way ads not shown only on my Firefox. Internet Explorer (IE) Adsense Ads work fine. All ads shown on IE or Chrome. Only solid color shown on Firefox all times. I have two sites http://www.studyinfo.pk and http://www.thepakinfo.com Please Help me, Due to this reason may Adsense revenue is going to low. <a href="http://www.studyinfo.pk" >www.studyinfo.pk</a> <a href="http://www.studyinfo.pk" >www.thepakinfo.com</a>