Regarding FF2 crashes with Firebug.

[John J Barton]

Here is what I know about FF2 crashes when using Firebug:

FF2 does not crash every time a certain operation is performed.
The stack trace from these crashes varies somewhat.
The probability of crashing is much higher with
javascript.options.strict true.
The probability of crashing is higher if you have Firebug enabled
for pages with Google pageads.
Numerous stack traces have been filed in Bugzilla, incl
https://bugzilla.mozilla.org/show_bug.cgi?id=317283
https://bugzilla.mozilla.org/show_bug.cgi?id=400618
https://bugzilla.mozilla.org/show_bug.cgi?id=400532
The problem is known to Firebug and Firefox developers

Speculation:

The problem is a garbage collection bug in the C++ debugger layer
over Firefoxes Javascript engine, the layer called JSD.
The problem is related to eval() scripts (though not to Firebug's
eval support).
There are two separate paths to trigger the bug, one by pumping lots
of errors into the observer event queue and another by pumping mouse/
window events, eg by changing tabs. These events create competition
for CPU resources that uncovers a bug that would otherwise be
harmless.
Firebug users trip on it now because 1) There are more of us now, 2)
we have Firebug on a lot, 3) Many pages include Google pageads script,
4) pageads does a large-ish eval() 5) many pages that include pageads
also have a lot of warnings and errors. 6) Firefox 2 is otherwise very
stable so this newly exposed bug stands out.
The bug will be hard to find, esp since no developer has been active
on JSD in years.

How it minimize your risk of crashing:

1) Set javascript.options.strict false
2) Use "Enable Firebug For this Site" not "Enable Firebug".
3) Don't enable firebug on pages with Google pageads.
4) Run Firebug and your daily browsing in different copies of
Firefox: see
firefox -no-remote -p "Another Profile"
on http://developer.mozilla.org/en/docs/Command_Line_Options

John.