Mac OS X + Firefox Issues

Hi,

I recently noticed a major alignment error on our website when viewing in Firefox on a Mac. For some odd reason, this error does not occur when viewing the website in Firefox on a PC. I am using the latest version of Firefox on both the Mac and the PC.

Does anyone have any idea why this is occuring?

The website is: Los Angeles IT Consulting and Managed Services - Barebones Networking

Below is a screen shot of how it should look, and how it looks on Firefox.
Although the correct screen shot is taken in Safari on Mac, it also appears correctly in Firefox on a PC.

Correct: (screen shot taken in Safari on Mac)
http://www.barebonesnetworking.com/wp-content/uploads/2011/08/Screen-shot-2011-08-31-at-11.55.42-AM.png

Incorrect: (Firefox on Mac)
http://www.barebonesnetworking.com/wp-content/uploads/2011/08/Screen-shot-2011-08-31-at-11.48.43-AM.png

It’s working fine for me on Mac (both in FF5 and FF6).