IOS 4 on 3G - Phone doesn't go into sleep mode when on a call

Question

I have a 3G iphone with the 4.0 OS. Whenever I get or make a phone call the screen does not go black therefore causing me to hit mute buttons and what not. I didn't have this problem on my 2g phone. I've tried to research it and look it up in the settings and I come up with nothing. How can I get this problem fixed ?

Answer 1

Same exact issue on my MacBook Pro. It is brand a brand new model: MacBook Pro (June 2009), with Mac OS X 10.6.1 and "7 hour battery".
Model Information:
Manufacturer: SMP
Device name: bq20z451
Pack Lot Code: 0000
PCB Lot Code: 0000
Firmware Version: 0003
Hardware Revision: 0003
Cell Revision: 0100
Charge Information:
Charge remaining (mAh): 6515
Fully charged: Yes
Charging: No
Full charge capacity (mAh): 6690
Health Information:
Cycle count: 27
Condition: Normal
Battery Installed: Yes
Amperage (mA): -936
Voltage (mV): 12311
System Power Settings:
AC Power:
System Sleep Timer (Minutes): 10
Disk Sleep Timer (Minutes): 10
Display Sleep Timer (Minutes): 10
Wake On AC Change: No
Wake On Clamshell Open: Yes
Wake On LAN: No
Display Sleep Uses Dim: Yes
GPUSwitch: 2
Battery Power:
System Sleep Timer (Minutes): 10
Disk Sleep Timer (Minutes): 10
Display Sleep Timer (Minutes): 2
Wake On AC Change: No
Wake On Clamshell Open: Yes
Current Power Source: Yes
Display Sleep Uses Dim: Yes
GPUSwitch: 2
Reduce Brightness: Yes