Iphone 3GS problem- error message keeps popping up

Just started this yesterday. It keeps popping up a message saying: "This accessory is not made to work with Iphone" and asks me if I want to turn on airplane mode. It pops up all the time. It was doing it yesterday whenever I tapped on any application, and now today it's just popping up on it's own when I'm not using the phone at all. I have turned it off, and have even done a soft reboot. Any ideas?

I generally only got that message when using non Apple branded accessories. Has the phone been wet at all? dropped? any kind of damage?

It's sounding like a hardware issue. You can try restoring the phone to see if that works.

that message sometimes pops up when i use a belkin FM transmitter but it still works...and if i unplug it and plug it back in it doesnt pop up but still work

No non apple accessories and no damage to phone. I guess I'll do a restore. It's still doing it.

you may just have some dust or something in the charging port. Lightly blow that area out to see if that helps.

Four calls to apple and four hours later, looks like it's a hardware issue and they're sending out a new one (it's less than a year old so warrantied). I dumped everything and restored it, and problem got even worse. If they even try and say the phone was damaged I'm gonna get medieval on them. I treat that phone like a child and it is perfect with zero damage. I wonder how honest they are with trying to charge people instead of covering you under the warranty. It's not like apple is hurting for money.