Problem of tab browsing

I get a strangle problem of using firefox in MacOSX, the tabs is hard to
click. Say I am in tab1 and want to go to tab2, I click tab2, but it
won't switch to that tab. I need to point the mouse pointer to some
where of tab icon so that it switch. Strangle, right?

It don't happen if I create a new profile, thus it is problem cause by
my existing profile, which port from windows to MacOSX. However I don't
know how to trace and solve the problem. I've try to disable all plugin
as well as remove all custom setting, but all don't work. Can anyone
give me some hint about that?