Introduced in Ubuntu 7.10 was a feature known as BulletProofX, which provides a fail-safe mode that is by default used when the X server fails to properly initialize. In this original implementation, it would default back to using the VESA display driver with 256 colors and then proceed to run the displayconfig-gtk utility. While this is nice for the end-user as it keeps them from touching a terminal to debug an X server problem, for experienced users it inhibits them from easily debugging the problem. This Canonical implementation also had frustrated other users. However, with the forthcoming Ubuntu 8.10 release, it has received some much-needed improvements while making BulletProofX more simple.
Back in July when Ubuntu 8.10 (the Intrepid Ibex) was in the middle of development, it looked like BulletProofX could be canned. Canonical's X.Org engineer, Bryce Harrington, had stated BulletProofX had a number of unaddressed bugs, displayconfig-gtk lacks support for RandR 1.2, and KDE is deprecating the guidance-backends. Because of these issues, Bryce was deciding whether to disable BulletProofX by default. However, with the just-released Ubuntu 8.10 Alpha 6 it continues to live on and has received some improvements that enhance its usability.
In Ubuntu 7.10 and Ubuntu 8.04 when X failed to start, the FailSafeXServer would load, which would inform them with a generic message that X had a problem and then would redirect them to using displayconfig-gtk to reconfigure the server. The displayconfig-gtk utility is capable of adjusting the resolution and changing the used graphics driver. Now when the X server fails and the FaileSafeXServer is called within the GDM configuration, the user can choose to either troubleshoot the error or reconfigure the graphics. These menus are powered using Zenity.