Rootkits have been in the press lately and it´s a good idea to be on the safe side and check your system from time to time to make sure it is not infected. I´am going to introduce two freeware utilities that scan your system and reveal rootkits if they are installed and running on your system.
The first tool is called rootkit hook analyzer, the second one rootkit revealer. Both are great tools and easy to use. You probably have to do some research on the web after one or both of the tools scanned your system. You have to interpretate the output, the website that can help you with this is either the rootkit revealer homepage which has a short introduction on interpretating the output or the rootkit.com website which has lots of information on the subject.

Check a system for rootkits with Gmer