browser getting hang

i have a HP G4 laptop & i installed 64 bit windows 7 in it .
now when i use firefox and try to open zbigz.com , the browser gets hanged and not responding .
i tried many things like installing old version , removing cache and doing tweaks but nothing worked . i already have flash player installed .
other sites opening fine but zbigz.com giving issue .
The site opens perfectly in IE and Chrome .
can anyone tell me exactly wats the issue . iam stuck in this since 4 hrs.