Internet explorer was not able to open this site The requested site is either un

I had IE7 and "Internet explorer was not able to open this internet site. The requested site is either unavailable or cannot be found" came up, so i searched around and found out it was the "Do not save encrypted pages to disk" reason, so i unchecked it and it worked fine, then downloading videos effected, so i downloaded adobe flash play update. I got the same problem again and have tried everything to fix this, i now have IE8 and i cannot download any files from any site and i cannot watch videos on youtube etc. So i got mozilla firefox and i can download files and watch videos and od everything without a trouble, but now i can stream free online tv, which annoys me greatly, if anybody knows why IE is failing me and why i cant stream free tv, it would be a great great help as this problem has been annoying me now for a few months and i am over using two internet browsers to do the same things basically. So if anybody can help either reply here or email me, Corey_Keeper@hotmail.com
I also have XP and not vista