Missing Content In Some Firefox Browsers

Hi.

We have put Paypal buttons on our front page next to a graphic for an event we are doing. It looks fine in IE, Chrome, Safari and most Firefox browsers. Someone in the office has Firefox on her laptop doesn't see the image or the buttons and some of the content from the left sidebar is showing up in the content area. Another co-worker said her friend, also on a laptop, sees the same thing. I don't know if being on a laptop makes a difference but I'm giving as much info as I can. Our site: http://www.insideoutca.org

My ED says I need to get someone in here to get this fix since I can't devote 100% of my time to this. So if this isn't an easy fix that can be explained to me, can we pay some one to come in and do it?

Thank you.

Stanley