URL

(...) And make sure you are on the latest version of CI,currently 2.0.2, (...)

The latest - stable - version of CI is 3.1.3, not 2.0.2 !

Adding a query string to a segment based url is no problem at all. E.g. this is a valid url:

Code:

http://www.mydomain.com/mycontroller/mymethod/?cat=pro&order=asc

This could be a url from a form that is using the get action rather than post.
Use this->input->get('cat') to fetch the value of the parameter 'cat'.