So, I've had the iPhone 3GS since launch day and have generally been very happy with it. However, twice since I've gotten it, I've had a problem where it refuses to turn on. It will be in standby mode (i.e. screen off), and I'll go to wake it up as usual (using the power button or the "Home" button) and it won't come on. Thinking that I've turned it off, I'll then hold the power button, but still no response. As far as I can tell, the only way to get it do anything is to hold down the power button and home button together for several seconds and it will finally power on (i.e. show the Apple logo and go through the standard restart sequence). Note that I have not turned the power off in either of these situations; I've just put it into standby. Something I just noticed after re-powering it on is that the battery indicator seems to be much lower than it should be given its charged state earlier and the time that has elapsed. Perhaps it was running some piece of software that was causing it to lock up? Any insight here? Have others had problems like this? Any idea on ways to test what the problem is?