mozilla javascript segment exception

[Anne & Lynn Wheeler]

recent builds of firefox/seamonkey on up-to-date F10 x64 worked fine yesterday morning

yesterday afternoon, same files after f11 x64 upgrade started failing (visiting most URLs requiring javascript & javascript enabled) with segment exception (under xfce, kde, & gnome). Problem shows up with both x64 and non-x64 builds of firefox as well as (non-x64 build) of seamonkey. javascript acceleration is enabled for firefox builds.

some random testing found a seamonkey build from last sept2008 that didn't fail