Re: Acer Aspire 4720 long shutdown problem soultion here.
I bought Aspire 5315 for a friend of mine and faced the same problem, so I did the following: "PS: the laptop came with Suyin webcam"
1- Install the Driver version 220.127.116.110 and the application V1.0.10 from Acer website.
2- Install the webcam driver and reboot.
3- Uninstall the device from add/remove programs and reboot.
4- Install the Suyin application.
I then tested the cam on both Yahoo and Live messenger, and it worked fine; no need to disable and enable the cam, and the system can shut down and stand by.