Currently Being ModeratedApr 8, 2012 6:46 PM (in response to myrustynail)
Are you using a case that might be blocking or partially blocking the proximity sensor? If you are using a case, remove the case to see if the same occurs without the case.
How long is a moment? Does this mean a second or two only?
What troubleshooting steps have you tried if any regarding the latter?
Currently Being ModeratedApr 8, 2012 6:49 PM (in response to myrustynail)
Not sure how to fix this, but that sounds like a problem with the proximity sensor (see http://www.macworld.com/article/1152412/iphone4_proximity_sensor.html). This was a more widely reported problem with the iPhone 4 during the summer of 2010. If you search these forums or Google this you may find a solution that will work for you.