I do have a question and a suggestion for you regarding the not being able to boot from a DVD issue...
Did you try tapping the ESC key at the beginning of the HP welcome screen to get the menu of options?
There you should see the F9 boot options menu, and you can select that, and then see if when you select the DVD drive if it will boot from the DVD.
The suggestion I have is perhaps you can ask that other forum member how he got his G2 to boot from a DVD, as clearly he had no problem with that on the same PC as yours.