Hav To fix ma code for firefox 3 :(

WE completed a project two months back, here at Raweng.Every features wrked as intended.Now a registration form is not wrking in firefox 3.Now i need to get a fix for it.Hav not seen the xact problem.But it’s wrking in all the browsers but not in Firefox 3.Works in Firefox 2 though.I dont know wat is da reason behind dis.Need to chk out.It wud be very disappointing if each code needs a fix for firefox 3.