I fixed it!
The problem was that I untarred firefox-1.5.0.5 in the wrong place. This procedure worked:
cd /usr/lib
tar xzvf firefox-1.5.0.5.tar.gz
I updated firefox, now java is broken. I searched about:config for java and compared to working computer, no change. I tried running firefox as root and as knoppix, no java.
I fixed it!
The problem was that I untarred firefox-1.5.0.5 in the wrong place. This procedure worked:
cd /usr/lib
tar xzvf firefox-1.5.0.5.tar.gz

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