[CentOS] firefox i386 1.5.0.5-0.el4.1.centos4

Hi all

I am using CentOS 4.3 and my default language is Japanese. I am using firefox with Japanese language. I installed firefox i386 1.5.0.5-0.el4.1.centos4 update 15 M on my computer via yum yesterday. CentOS 4.3 has been acting strange! Japanese language on firefix has gone and English seems to be default language on firefox. I simply removed firefox 1.5.0.5-0.el4.1.centos4 and reinstalled firefox 1.0.7-1.4.3.centos4, so I can use firefox with Japanese language. Would you know why this is happening? Is this happening only to me? I installed firefox extensions on firefox 1.0.7-1.4.3.centos4. Does it affect on firefox i386 1.5.0.5-0.el4.1.centos4? Thanks.