USB Port Not Working on Macbook Pro Late 2011

Hi,

I have two USB ports on the left hand side of my Macbook Pro Late 2011. The one closest to the power adaptor is not responsive. I've looked on the internet forums for answers, and have already reset my PRAM and SMC but still am having these issues. The resets resolved the problem for about 90 seconds then port stopped working again. The other USB port still works so I don't know what to do. I am trying to connect a Lacie ext HDD and a Microsoft 3500 Wireless Mouse. If anyone has any idea what I can do, please let me know. Thank you.

Some details:

13' Macbook Pro Late 2011

Version 10.10.2

2.4 GHz Intel Core i5