This occured for me on a semi-fresh install of Ubuntu 8.04 beta. Semi-fresh meaning that I installed, enabled all the optional repos, threw on the nvidia-restricted drivers for my 8600, enabled compiz and browsed to www.ubuntu-guide.com. Every time I attempt to visit that site in firefox on this install, X restarts.
This occured for me on a semi-fresh install of Ubuntu 8.04 beta. Semi-fresh meaning that I installed, enabled all the optional repos, threw on the nvidia-restricted drivers for my 8600, enabled compiz and browsed to www.ubuntu- guide.com. Every time I attempt to visit that site in firefox on this install, X restarts.