I took lots notes in iPhone 3Gs for my meeting, but when I was at the meeting and my iPhone just freezes on me. I was totally lost without my iPhone's notes... But luckily I brought a charger with me and after plug in my dock charger and it start working again... Seriously, anyone got ideas on how to fix issues like this? or anyone have experience this type of issues?

Product Link: http://www.handhelditems.com/iphone-3g3gs-apocket-mutifunction-1750mah-backup-battery-case-p-121596.html