What's wrong with my computer?

Alright, my computer has been acting weird. All of the icons on my desktop either have the whole icon or just the text surrounded by blue. Whenever I'm on Firefox sometimes the page will switch itself over to an avertisement page. Usually when I get on I got into taskmanager and get rid of all the unneeded programs that are running. I'm pretty sure I have adware, too, since so many popups keep coming up when I'm on the web.

What's wrong and how do I fix it without spending any money?

What's wrong with my computer?systemworks

Go to Ad-Aware SE and download their free program. Also, go to www.download.com and go to the spyware section and get spydoctor. That'll clean up the crap and keep your page from redirecting. Good luck, and watch our for that porn.

What's wrong with my computer?windows

reformat your computer and reinstall windows
download spyware cleaners. google it up.
go to www.download.com and download ad-aware and spybot, update them both and run them to get rid of all the spyware that's prob on your computer
spybot S%26D

Windows Defender

Mcafee.com has free antivirus scan and manual removal tools

I'd get Adblock plus for firefox with the filterset.G updater

Run Defender and S%26D in safe mode. After that run msconfig if you are using XP (start --%26gt; run --%26gt; msconfig enter). Go to startup and remove any program that doesn't look critical to your daily operations. Good luck
sounds like spyware or adware, get adawarepersonal se it fixed it for me although i have to run it at least once a week.
Probbaly a virus.get a firewall.

Did i help any?
You should get a firewall also, in addition to everyone elses suggestions. I would recommend a hardware firewall, but since you want free- I run Sygate Personal Firewall (currently owned by Symantec), and it doesnt come up on download.com any more since being bought out, but you can find it if you search around a little bit. And the best part is, its free and works great