Frequent crashes Mozilla 1.6 & OSX 10.3.3

Recently I was having some trouble with my Mozilla 1.5 installation 
crashing while web browsing after a long period of good stability and no 
problems. I upgraded to Mozilla 1.6 hoping that would help but now the 
instability is even worse. Is this any sort of known issue, or how 
should I go about doing a truly "clean" install of Mozilla? When I 
upgraded, I trashed the old 1.5 binary and replaced it by dragging the 
1.6 binary to the applications folder. Is this no good? And what might 
be causing these crashes? I can post the feedback sent via the Apple 
crash report if that would help.

Thanks for any help,

Steve