IGR stands for In Game Reset
People where asking if anyone could make a way of using a combination of keys on the controller to make it possible to reset the xbox. This option is very cool when your launching software from your xbox harddrive.
Both Team Executer and the guys from EvolutionX made a way of doing it.
Team Executer included it in their BIOS for the ExecuterII ( also available in 256kb so it can run on matrix and homebrew ). Supported since release 4972 ( which had some problems with a few games ) so try using a newer version.
For the X-2 BIOS reset, L + R + Back + Start or L + R + Back + Black
The guys from EvolutionX included the support for IGR into their EvolutionX Dashboard. It is supported since release 1.8.3285.
For the EvolutionX dash reset: L + R + Back + Start
The only real difference between the 2 versions is that the ExecuterII method reboots to the dashboard, and the EvolutionX method does a hard reset of the xbox itself. Both are a good solution to the "i am to lazy to walk to my xbox and press the on/off button" so all you Fanboy's out there don't start flaming one or the other.
I saw this information posted by knowledgeive on the forum and thought that it would be usefull for some people, so all credits to him