After some research, I found out that it isn't just Firefox that causes this crash. It can be reproduced in Kate, Konqueror, etc. It seems to be caused by certain really long strings such as the one in the attached HTML file posted earlier.
I ran across a post on the NVIDIA forums of others having this problem, and it is fixed completely for me with the latest drivers, version 1.0-9625. -- reproducible X restarts involving GdkPixbuf-CRITICAL https://launchpad.net/bugs/51425 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
