Laptop acoustic feedback
I have two Acer's Aspire laptops, a 5920G and a 5470 both running Windows 7 Home Premium.
When I run the 5920G laptop with the internal speakers and internal microphone turned up it performs well and I have no problem using Skype.
When I try to use the 5740 with the internal speakers and internal microphone turned up I get acoustic feedback, i.e all sounds local to the computer are amplified and played back through the speakers. If I use a USB microphone the problem is cured.
What is going wrong?