[CentOS] unexpected mass closing of terminal windows

Hello,

I apologize if this isn't quite the right spot to ask, but I did some
googling on fc6, rhel5, centos5, terminal closings, etc and came up blank.

Three times since I installed CentOS5 on this machine (11 days ago), I
have had ***all my my terminal windows spontaneously exit***.

For example: just now, I have a CD playing, firefox open with a few tabs,
and emacs open.  I also had ~5 terminal windows open, one for email and
four for work.  While typing an email on a remote machine in pine, *all*
of my terminal windows exited.  Just plain disappeared.  Everything else,
including the emacs copy started from one of those terminals, is running
fine.

It's a frustrating thing to see happen!  Has anyone else experienced this?

This is in the gnome desktop, x86-64 install, all the latest updates from
yum.  The machine is a nforce3 board with 1 gig of ram, Athlon64, sata
drive, and NFS mounted home directories.

Thanks,

Brian