Q:

Firefox, one browser, but two different versions?

I our web application is compatible with Firefox 3.6+ 
We have a Firefox installed on one of our local machiens and on the top of the about page, the version is set to 3.6.10 which is what we expect.
On the bottom of the about page, the version is set to: Gecko/20100914 Firefox/3.0.1
Because it's set to 3.0.1 it gets picked up by client side script and the user is unable to use the application. Currently I'm unable to replicate this. 
Our guess is that user didn't install 3.6.10 from scratch, but updated from 3.0.1
Did anybody else come across this before?
Thank you
Edit: The Gecko version is "Gecko 1.9.2" which comes with Firefox 3.6...so that's also fine.... very confused
Edit 2: IIS LOG
Mozilla/5.0+(Windows;+U;+Windows+NT+6.1;+ru;+rv:1.9.2.10)+Gecko/20100914+Firefox/3.0.1+(+.NET+CLR+3.5.30729;+.NET4.0C) 200 0 0
I can see the 3.0.1 but I don't understand why About page displays a browser version as 3.6.10
Also if you look at the GECKO version from IIS log, it's 1.9.2 which is supplied with Firefox 3.6.*
Edit 3: The problem was in a FireFox .config file which has been manually edited/spoofed 

A:

I strongly suspect your client has a modified user agent string.  You can reset it by following these instructions.

