MiFi and MacBook Pro

Hey guys, Help! LOL.

My mom loved my Macbook pro so she just got one of her own about 3 weeks ago. At the same time she bought a MiFi. The Apple support lady on the phone had NO CLUE what a MiFi was! So I will tell ya'll just in case. This device allows my mom to use the internet wireless on up to 5 different devices at one time. It is from At&t and uses a SIM card and it is a really cool piece of equipment if you ask me.
Well she has been using the MiFi and the Pro together for 3 weeks and it works fine. This morning the MacBook was still connected to the network but would not load the internet. Her Iphone, my Iphone and he Dell laptop would connect and worked on the internet fine so it is NOT the MiFi!!!! LET ME STRESS! NOT THE MIFI! Ok? Good.
What could this be? We have restarted the computer and the router. We have cleared the cookies and catche and we have reset Safari.
Any other suggestions? Thanks in advance for the help guys!

The Mifi is a cool device. I have one for Verizon.

Firstly - is there any other wifi network you can try? It may be some hardware got fried and if no other network works then it is probably hardware related.

Secondly - you could try deleteing the Mifi network and rejoining it. System Preferences -> Network -> Airport -> Advanced -> select the mifi network and hit the - button. Then try to rejoin. You may also want to turn all security off - just as a test to see if the MBP can join a completely open network.