Bumping this because I ran into an issue, found a solution.
IF YOUR GT750 is turning itself on automatically, please read.
Green flashing light all the time (slow flashing) - running, powering on, powering off, and off - always slow flashing
You do not see the standby light when the projector is off (you still see the slow flashing green light)
Projector turns itself back on after being shut off. It may try to, and then wait, and try again (its waiting for the bulb to cool)
1. Go into the menu > OPTIONS > ADVANCED > DIRECT POWER ON - TURN THIS ON
2. Exit the menu
3. Power down the projector
4. Now, wait 10-15 minutes for the projector to cool. Serious on this.
5. Power on the projector, go back into the menu and turn OFF the DIRECT POWER ON feature
6. The next time you shutdown your projector, you should see the green light turn off, and the standby light should come back.
Since this happened not long after I got my first lamp warning, Im going to assume its a corruption issue in the firmware. Ive read on other forums of users having this same issue over 500 hours (ie, when you get your first lamp warning).