I'm using Windows XP. I use both the latest IE and Firefox 2.0.
Awhile back, I needed to speed up my computer, but I'm not sure now
what I deleted. Problem I have now, is that for both browsers, if I
want to go on a website like ifilm.com or youtube.com,although I can
get to their main page, if I try to go any further I get a message at
the bottom in FF that says "Looking up ad.doubleclick.net" And then
it hangs. Same thing happens with a different message in IE.

What can I do? I could use System Restore if that would help undo
what I did - whatever it was I did.

Thanks,

Rick