Cannot access windows update, support, hotmail

I cannot access any microsoft site like windows
update, support.... I also cannot access a couple of yahoo
mail accounts which actually work perfectly on other
computers. I also cannot access launch on yahoo. However
the rest of the internet works perfectly. The problem came
out of nowhere.
I have tried a lot of things, like removing all of
the temp content, and flushing the dns. ia also checked my
security options. I also formated my hard drive but the
problem persists even after a clean install. I recently
updated to SP2 but the problem is still there. it is
fustrating how i cannot use the microsoft sites.
If anyone has a sollution to this you would do me a
great deal of good. Please write to me!!!!!!