In many cases once the "intruder" is on your system then even...

In many cases once the "intruder" is on your system then even though you uninstall the problem it will reinstall itself once your machine is rebooted.

You could do a "run" "msconfig" and look at the startup services to see if there is anything strange there.

Alternatively, an extremely useful program is Hijackthis.

http://www.majorgeeks.com/download3155.html

This is a great utility and will locate every problem on your system.

BUT read the warning, you need to have a bit of an idea what you are doing when deleting files.

There is no problem in downloading and installing the program so you can do a run and see the results - you don't need to act on what you see.