A worm has been planted in your computer, funneling SPAM advertising from the internet.
Delete current antivirus software, turn off windows firewall.
Run Panda Internet Security Active scan (use Panda only, don't fall for any free "cleaner" software)
Then Install Panda Internet security (trial 30 day version)
This will keep the crap out.
1. NEVER download "free antivirus" or "free system cleaner" software.
2. You get what you pay for. If it's free, you will be sorry later.