Spyware....argggh!

So my girlfriend’s mother asks me to check out her laptop because she continually gets pop ups “alerting” her that her computer has a virus on it. After numerous attempts to remove the spyware to no avail, I’ve almost given up.

Can anyone recommend a good, and preferably free, spyware remover for windows? I’d really hate to have to reinstall windows but it’s incredibly frustrating for her mother. Plus, brownie points are awesome.