Problems with Firefox

For quite some time now, Firefox version 3 has been crashing so frequently that it is almost useless. It loves to crash when I am in the middle of writing a post. Each time it sends a crash report but nothing changes.

Firefox 3.5 is too top heavy to function on my main computer which has Pentium III 1 GHz and 320 MB RAM.

So I am using Flock which seems quite stable. Is anyone else experiencing problems with Firefox?

BTW I have found it is possible to download earlier versions of Firefox (2.0 for example) if required. I cannot detect any improvement in more recent versions.