www/firefox: Firefox 3.6 crashes, Firefox 3.5.7 not

[O. Hartmann]

Today, I upgraded Firefox 3.5.7 (built yesterday) to Firefox 3.6. After 
deleting ~/.mozilla (after I did a buckup, of course), I tried a fresh 
start of 'firefox3'. After firefox showed up, I realized that no 
option-field (File, Extras etc) can be used, they are dead and after a 
few seconds I clicked them, firefox3 is crashing.

Since I recompiled firefox 3.5.7 yesterday I was wondering if this is 
due to some 'false' lib or dependency. Since I figured that I have 
similar trouble with Thunderbird 3.0.1 after I installed it, I suspect a 
faulty library causing this behaviour. With Thunderbird 3, I never 
solved the problem although I tried to rebuild everything with 
thunderbird via 'portmaster -f'. I'll did this with firefox 3.6 also, 
but with no success.

The crashing is observed on two nearly identical SMP FreeBSD 8.0/amd64 
STABLE boxes (make world of today), up-to-date ports. The crash is NOT 
observed on my private oldish UP box, nearly the same setup, OS at the 
same revision and ports up to date as of yesterday. Maybe this could be 
a hint.

Any hints or suggestions?

Regards,
Oliver