For one thing, Worms are nasty little buggers. The big problem is that they are always active. As such, they can be difficult to handle. They continuously put viruses into your computer that can cause quite a few problems.
Top choices when it comes to free scanners that get rid of worms are as follows:
Avast! Antivirus
Malwarebytes'
SuperAntiSpyware
At least those are my main three choices. Use one of those, and you should be fine.

Also, with any Antivirus, make sure you have the latest updates. Do that with AVG, clean them out, and see what happens. If that doesn't work, go with one of my recommendations, making sure to have the latest updates.
Trust me, you'll be thanking me for this.
