Do the following:
- Disable all plugins and third party add-ons - you can do this from the menus and/or by some setting in about:config
- Try again. If that doesn't fix it, also erase your profile.
- If it still crashes, try a reinstall
- If, after a reinstall, with no third party plugins or addons, it still crashes, you MUST file a bug report on Bugzilla.
The only way software can improve is if people report bugs!
By the way, it is highly likely that a third party plugin (especially Flash) is crashing it, not the Mozilla browser itself. The problem is, that many plugins frequently issue updated which break Mozilla; this is not Mozilla's fault.
Mark