Help, slow scanning!

[UNiVERSE]

I know I'm infected by something because visiting a site a few days ago, norton antivirus found some viruses and other programs detected some changes of the default internet explorer page and search page. After having done a bit of scans with various programs (even online scan) I was able to delete some viruses and spyware that were not detected by the other programs I use, but now I have a strange problem... for example when I search for something on google, some sites open in a page in which there are always the same spots and ads, ("Enter Keyword - Search!", travel, professional services, legal help, financial planning, new technology, etc.), ONLY the site name changes, the style remains the same, this only occurs on some sites that cannot be opened. I get a really slow scanning with Spybot Search & Destroy, 2 days ago it took almost 2 hours for a scan... I get some hangs in some areas, for example at #643, Central24... and other that I don't remember. It takes a pause of about 1 minute everytime it hangs... However nothing can be found at the end of the scanning, I think like something is hijacking spybot search & destroy, what can I do to discover what's wrong?
I already did an online virus scan on micro trend housecall.

My pc specs:
cpu amd sempron 2500+ 1,7ghz
motherboard biostar m7ncg400
ram 768mb 333mhz
graphics card sapphire radeon x800 pro
hard disk maxtor 80gb

Please, help!

[tashi]

Hi there.

Please go here and follow instructions.
Before you post a log (http://forums.spybot.info/showthread.php?t=288[/url)

Start a topic here:
Malware Forum (http://forums.spybot.info/forumdisplay.php?f=22[/url)

Someone will then take a look at the system and advise you. :)