Currently Being ModeratedJun 29, 2013 2:13 PM (in response to bluepez)
Great job testing on a different network, now we know its something on the computer that needs to be troubleshot.
I suggest resetting the SMC on the computer first, with this article:
Intel-based Macs: Resetting the System Management Controller (SMC)
If that doesnt resolve the issue, I recommend the Symptom: My Mac does not connect to the Internet of the article named Wi-Fi: How to troubleshoot Wi-Fi connectivity found here http://support.apple.com/kb/HT4628?viewlocale=en_US.