Recently, my FSX time has increased and that means seat time in the NGX. My computer is mid to high end and tweaked for stability and visual quality, FSX has never been better. Then I do something that both embarrasses me and at the same time reminds me how cool the NGX is. I was flying UAL 1539 TPA to ORD in a 739 and went through my normal routine except this time I have GSX. Long story short, I got an alarm on the pressurization panel showing it could no longer "Automatically" control the pressure and I got glitches with the altimeter during approach where it would blink from normal to zero and back.. Very strange, so I inspected my aircraft and realized that the cargo doors we're still open. haha, what an idiot! I was thinking prior to my cargo door discovery that "hmm, this must be some kind of service based failure". Haha nope, just human error.