Go here:
http://www.ad-aware.com
and download ad-aware. Install it, run it.
There's a button to check for updates - do that.
Then run a scan, and it will look for all the miserable little adware programs that get installed on your computer. Since you're new and don't know to watch out for these, you probably have a zillion of them. They can cause this.
It will probably want to reboot your computer, then will run again after you reboot to remove the last of them.
Finally, go here:
http://toolbar.google.com/
Download and install the Google toolbar. It blocks popups, which is what a lot of these programs use to install themselves.
After that, once in a while, run ad-aware again. It's good to run it at least every couple of months if not more often.
If you don't have an anti-virus package, get one. I like Norton Internet Security. Get it here for $34
http://www.directdeals.com/Item_CD-10098800.aspx
It also has a very good SPAM filter tool, and some firewall tools. It helped my mom and dad out a lot.