How do i get Spyware off my computer?

i'm using avast anti virus. Today i got a "system alert" that my computer may be infected with spyware. Nothing was found after scanning. Yet said "alert" pops out everytime i boot up. Worse, i've been directed to a girlie porn site many times instead of (non-porno) sites i chose to visit.

How do i get Spyware off my computer?vincent

I use AVG, Ad-Aware and Spybot Search and Destroy. It is always good to have a mixture of programs because while none are perfect, you can keep your system clean with a few. The ones I use are all free.

http://www.download.com/3640-2239_4-1078...

http://www.download.com/3000-8022_4-1076...

http://www.spybot.com/en/index.html

If you don鈥檛 want to download, try running some of these online scans. Online scans allow you the privilege of cleaning your system when a virus will not let you run you protection. Find them here:

http://www.infectedornot.com/usa/

http://www.nanoscan.com/as/index/

http://www.virustotal.com/

http://www.cyberdefender.com/

http://housecall.trendmicro.com/

http://www.garbageclean.com/

http://secunia.com/software_inspector/

Some people have good results with CCleaner. CCleaner is a free program to benefit your system and increase your privacy. It removes unused files from your system - allowing your computer to run faster and get more space on your drive. The program can also clear system history. This program contains no spyware or viruses and is a safe download. Find it here: