"Failed to load" or "Failed to start" errors when trying to start the graphical desktop environment (X11) on BackTrack 5 KDE can be caused by a variety of factors, including problems with the X11 configuration, driver issues, or problems with the desktop environment itself.
Here are some steps you can try to troubleshoot and resolve this issue:
Check the X11 configuration: Make sure that the X11 configuration files (located in the /etc/X11 directory) are set up correctly. You may need to modify the xorg.conf file or create an xorg.conf.d directory with appropriate configuration files.
Check the drivers: If the X11 configuration appears to be correct, the issue may be caused by problems with the drivers for your graphics card or other hardware. Try installing the appropriate drivers and see if this resolves the issue.
Check the desktop environment: If the drivers are installed correctly, the issue may be with the desktop environment itself. Try starting the X11 server manually using the startx command and see if the desktop environment loads correctly. If it does not, you may need to try a different desktop environment or seek assistance from a qualified technician.