iPhone 3G gets down when not connected
iPhone 3G was working fine on iOS 4.2.1
suddenly, due to some reason, its getting crashed/not working with just a blank screen.... no hard reset !!
and then if plugged in charger or USB, Apple icon comes in and after few minutes, its working absolutely fine till its connected either to charger/USB.
Initially, i wondered whether its battery problem, but... once iPhone is in on state... battery percentage is Max.
I tried restoring it but no effect on my issue.
please advice...