apps won't stay open

Upgrade to iOS 4.1 which is the latest.

I'm having the same issue. I've upgraded to 4.1 and every time I try to send a text, as soon as I start to type, it flips back to the home screen. I've shut it down several times. Same thing. Any suggestions? Very aggravating.

Try resetting your iPhone by pressing the home and sleep buttons until you see the Apple logo, ignoring the slider. Takes about 5-15 secs of button holding and you won't lose any data or settings.

that didn't work either.

Try texting and/or replying to a different person(s). If still a problem, the next step would be to restore with your backup.

I've restored it and it's still happening. Not all of the time, but most of the time when I tap the text bubble, it will open and then flip back to the home screen. It's such a nuisance. I guess it's time to call apple.

Do you have any 3rd party texting or keyboard apps? If so, try removing them.