Firefox 4.0.1: Firefox is out (of memory) !

I've been running various builds of Firefox 4 on Linux since the betas were beginning, months ago.  They were very stable.  And then 4.0.0 was released, and recently 4.0.1, and with both I've had a lot of crashes.  What's worse is that I cannot submit crash reports and no one on irc.freenode.net #firefox seems to know why (or they just won't answer).

When I run these from the command line, I see 'Out of memory' but I have 4 GB of RAM and 2GB of Swap space.  I am not out of memory, Mister Fox.