Wireless Connecting Problems

I have a 2009 MacBook Pro. For about the past week, whenever I try to connect to my home wireless a window pops up that says "Select a certificate or enter a name and password for the network [wireless network]" with a drop down menu that says "No certificate selected" and two input boxes for "Account Name" and "Password". I try to input my wireless account information but when I hit "OK" my info gets erased and nothing happens.

I have found a work-around but it's cumbersome and annoying. I can open Network Preferences, disconnect from my wireless, then reconnect and put in my password. Sometime it works on the first try, sometimes it takes 3 or 4 times. This box keeps popping up all the while.

I Googled the lingo in the box and it's coming up as a 802.1X network connection, which is apparently a higher sercurity setting for business and education internet connections. I have no idea why this started popping up suddenly. There's nothing I've changed either in my wireless settings, my router settings, or my computer that would trigger this. I updated to Mountain Lion right when it came out so I've had it for a while now with no problems. Also, my husband has a brand new 2012 MacBook Pro and there is no problem with him connecting to our wireless. I also have no issues connecting to other wireless networks (I just brought my computer over to a friend's house today and had no issues connecting to their wireless).