Multilib Firefox odd behaviour
 

Built Firefox 3.5 against Xulrunner 1.9.1 on a Multilib x86 system.

1) Firefox-32 segfaults on startup
2) Firefox-64 runs fine, but hangs on opening preferences, downloading a file, visiting gmail, nytimes.com, essentially anything that requires a plugin.

3) Firefox-32 can be launched while Firefox-64 is running. In this case Firefox-32 also hangs as in 2)
4) After a session with both browsers as in 3) Firefox-64 won't load again until removal of ~/.mozilla


I guess 3) means that Firefox-64 is loading some libraries to memory that Firefox-32 (or xulrunner-32) fails to load by itself. But besides this, I have no clue how to even start diagnosing the problem. Do you guys have any idea?

Thanks

R.