Can't change the menu

I'm using gnome 2.0 on RH 9.  Recently, I upgraded from firefox 0.8 to 
1.05, but I can't change the properties of the firefox item on the menu 
to point to it.  When I try, I get an error that it cannot samve changes 
to the launcher: "Error writing file 
'applications:/Internet/net-firefox.desktop': Read-only file system.  I 
get this even if I'm logged in as root.  I also get this if I try to add 
thunderbird to the menu.  Does anybody know what's going on or how to 
fix it?

-- 
Things aren't always as they seem
skim milk masquarades as cream!
  --Luke Redbeard