strange happenings with my esteemed firefox

Hi all.
Before I start griping about the computer, let me just say this site has alot of smart folks as members, as well as being one of the nicest sites.

Now to today's confusion. I was trying to update Firefox, which I have been using for a couple months instead of ie. I really like Firefox. The update turned out to be a new version, 3.5.5, and I have 3.5.2, which I wanted to keep. There was nowhere in the update to cancel, so I just x'ed it out, thinking it then wouldn't download, but when I checked my installed programs list, there 3.5.5 was. I uninstalled it, but couldn't find my old version on the site, so I started to download 3,5,5, and over halfway thru ie came up, said the file was corrupt, and ended the download. Well, I re-downloaded after turning off the windows xp firewall, and it seemed ok, but I couldn't get my old mozilla 'opt out of everything'cookie. I got a message from firefox saying it couldn't retrieve the cookies. So I manually downloaded it. I am just worried that all isn't well. Do you think things are ok, or is there something else I need to do? Would also mention that while using ie to get to Firefox, the same yahoo search hijack occurred that I posted about on this site so many times. I'm assuming the 'opt out'cookie from firefox when I first installed the earlier version eliminated that, as I had no problem with it while using firefox. The earlier version of firefox prompted me to add that cookie, but this version gave me the trouble I've mentioned, rather than recommending it.
sheena:confused