Every time I turn on my moms computer there is a ad for anti-virus software. There is no way to close it or click anything else on her computer. The Green Start isn't there. The only thing you can do is click on the purchase button and it takes you to a credit card order form. I can't seem to get rid of it. Does anyone have any tips?

You need to Run a spyware / antivirus scan to get rid.

Yes, she clicked on a ad that was going to give her a "free" check up, but what it does is put malware in the computer. So they basically hijack the computer till you either find a way to rid it of the program or pay the company for their services.