If you use the display rotation function in Mac OS X with your Power Mac G5 (Late 2005), you may notice if you reinstall Mac OS X that the installation screens are not rotated and you may see some distorted video.
If you see this, be assured that it will be resolved once the installation is complete and you have restarted the computer. If you don't want to tilt your head during the installation, rotate your display back to its standard orientation temporarily—you can rotate it back after finishing the install.