download from MG ruined things on firefox

Hello, just joined.
Yesterday I went to your site, MG to download an older version of Firefox for an older computer that I like better than my new one, and still use. I trusted your site, have downloaded successfully and without getting malware from it before. On the top of the page was a message saying that before I download I should run a scan to see what errors and so forth could be slowing my computer. Thinking it was an ad, I looked for the word ad, saw nothing. Still, I decided to just download the firefox but when I started to this popped up and started downloading, and thinking it might help, I went with it. It had to do with AVG, a well know anti-virus, so I still trusted. Some of the options I unchecked, but they got downloaded anyway, others downloaded too fast for me to uncheck them. This program removed my homepage, all my search engines, which it replaced with "avg safe search", and other crap. I tried to uninstall it. It would not uninstall. I then manually tried to uninstall, at first it came back, now I think I got it but may have harmed important files. Tried to uninstall Firefox so I could reinstall a healthy firefox, but can not uninstall it. I deleted the avg search engine, but now instead of the colorful google symbol in my I guess, navigation or search box at top, there is just a blue box with g in it, and I have lost all my other search engines. I went back to your site later that night and could not find that avg related program , which had been at the top of the download page in blue letters. I hope someone can help me with these problems. I am not at all computer literate, so would appreciate simple language and step by step. Thanks.
rachael17

 

Greetings, rachael17, and welcome to MajorGeeks.

Sorry that this has happened to you - I know it must be frustrating.

I strongly suggest that you perform all of the steps listed in the Read & Run Me First guide, then start a new thread in the Malware Removal Forum and attach the requested logs to your first post(s) in that thread.

When the Malware Removal gurus deem your machine as being clean, please post back here and we will help you with any further problems. Good luck!

 

Thanks Plodr and Caliban. Plodr, I already manually removed as much of the avg thing as I could, and may have removed some things I need. Are you recommending that I download Firefox 25 as I am running xp prof, ser pack 2. This is the first time I have had a problem with the internet on my old machine. I don't think I have the memory for Firefox 25. When I updated FF about a week ago it only went to ff12. I cannot uninstall the current firefox, and the colored google symbol isn't in the search bar, and when I click the arrow there none of my search engines come up. I manually went to google and made it my default, but am missing the others. How do I get rid of this firefox 12 and download a healthy version?

 

In other words, the avg thing messed up my Firefox. Yes, I was trying to download ff 11 as didn't like 12, when the avg thing started downloading.