Hello- I am also seeing this crash for all XUL apps on my machine, a PPC running sid (with iceweasel 3 and xulrunner-1.9 pulled from unstable). I've tested iceweasel, mybrowser, and xulmine as suggested in an earlier posting.
Let me know what I can do to help. If there is an earlier version (b5) that works available somewhere, that would be most helpful to get things running in the meantime. -- I cryptographically sign nearly all my emails with PGP/gpg. If it isn't signed, it's probably not from me! If you have the capability, please encrypt responses.
signature.asc
Description: OpenPGP digital signature