IE6 & Firefox--Page Cannot Be Displayed

Hi.

I submitted this problem to the malware removal thread and performed all the scans recommended. I submitted all of the logs and was told that they looked fine, so I probably don't have a malware problem. They told me to submit my problem to the software thread.

I have a used computer with Windows XP and SP2. I do not have a bootup disk--my brother-in-law was going to throw it away when his office upgraded computers, but he gave it to me instead. It came loaded with IE 6.

Back in June, I went to www.pcnineoneone.com and followed their tutorial about how to speed up an XP computer. That's about the time my current problem started.

Since then, I get a "Page Cannot Be Displayed" error whenever I:
(1) click on a Google ad.
(2) go to certain secure sites, like Clickbank.
(3) click on a link from a different search engine, like Goodsearch.
(4) view ads on any webpage.

Recently, IE 6 won't always connect me to the internet, so I downloaded Firefox, which has been reliable for me. I've tested and I know it's not a connection problem.

I have done a lot of research on Microsoft and followed a lot of their troubleshooting ideas, but the problem persists.

If the easiest thing for me to do is buy a bootup disk, should I just do that? Would it take care of my IE problem?

I have included an attachment with the steps I had to take on www.pcnineoneone.com so you can see what I did to my computer. In that same attachment, I included the comments from the person on the malware thread removal. He/she wanted me to get another opinion on the advice he/she offered, so I copied his/her post (lengthy) into the same attachment.

I would be so grateful for any help you could offer!

Thank you,
Kimberly