I have a problem with my iphone.

When I open my iphone from sleep mode, slide to unlock and go into springboard, no matter which application i press, it can go in for couple seconds, then it will jump right back into springboard. If i wait for around 30 seconds and do nothing, on the center of the springboard will show the loading circle, after it finish loading it will jump back to home screen (slide to unlock screen). Then i go in again everything works fine.

Why is that?

that only happens if the phone was in sleep mode for couple hours... very weird.
other then that, my phone works perfect.

Did anyone run into the same problem? is there any way to solve this? or maybe is caused by 3rd party application?

Thanx