Your user agent is corrupted:

Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.2.8) Gecko/20100722 Firefox/3.0.6, Ant.com Toolbar 1.3 ( .NET CLR 3.5.30729; .NET4.0C)

You have or had an extension installed (Ant.com Toolbar) that has changed the user agent to Firefox/3.0.6.

You can see the Firefox version at the top and the user agent at bottom of the "Help > About" window (Mac: Firefox > About Mozilla Firefox).
You check (compare) what websites see: http://whatsmyuseragent.com/ - Whats My User Agent?

You can check the general.useragent prefs on the about:config page.
You can open the about:config page via the location bar, just like you open a website.
Filter: general.useragent
If general.useragent prefs are bold (user set) then you can right-click that pref and choose Reset.

See Web sites or add-ons incorrectly report incompatible browser and Find what version of Firefox you are using

Can someone advise an easy way to fix this? I am having the same problem, but I am very novice at some parts of the computer, this being one of them, so I am not sure where the config page is. Thanks.

Do you have a corrupted user agent?

Help > Troubleshooting Information

See:

• http://kb.mozillazine.org/about:config