Hi there, just an update three years later. This problem can often happen when the security encryption key does not match or the computer wireless drivers do not support the encryption on the access point. If other computers have no problem connecting to the AP then try the following.
Delete the saved wireless profile for the SSID of the AP you are trying to connect to, this is under the properties of your wireless adaptor. When you try and connect again it will ask for the password again and make sure it is typed right.
If this does not work then update the drivers for the wireless adaptor in your computer, incase they are out of date. If it still does not work then use WPA-TKIP encryption on the AP as I have found this to be very compatible with most wireless cards.
Cheers, Dale.