firefox 4 with macosx 10.5 (leopard)

I run macosx 10.5 (leopard).  Today, I decided to replace my Firefox 3.x with Firefox 4.0.  Then I tried to call Firefox Profile but failed:

% /Applications/Firefox.app/Contents/MacOS/firefox-bin -P -no-remote
dyld: unknown required load command 0x80000022
Trace/BPT trap

Zzz... I just CAN'T LIVE WITHOUT FIREFOX PROFILE!!!

OK, thanks to asqueella.blogspot.com!  I have no idea what he is talking about but the solution is to:

% arch -i386 /Applications/Firefox.app/Contents/MacOS/firefox-bin -P -no-remote

Reference

• http://asqueella.blogspot.com/2010/12/dyld-unknown-required-load-command.html
• https://bugzilla.mozilla.org/show_bug.cgi?id=602049