Download Mozilla firefox 4 Beta 2 build specially designed for the users of 64 bit Windows-operating system from the ftp servers. Earlier 64-bit Mozzilla firefox 4 build was arrived but not able to run due to unavailability of MSVCR100.dll file. That’s required for Microsoft’s file to run the build.
One has to separately install MSVCR100.dll file in order to use the 64 bit mozilla firefox 4 web browser. However that issue is solved in the 64- bit Beta 2 build of firefox 4.Just download mozilla firefox and then test on 64-bit Windows operating system.