I Need Help!!! Please!!!

hi, i really need help. ok, well, certain pages on my computer are not working! they worked a couple days ago and now keep opening pages saying its not working. now, its only doing this on my regular computer and laptop. but friends of mine can get on those pages on their computers, so its not the page.
please tell me why its doing this? is it my computer or what? how can i fix it? or did somehow i get blocked from those sites? i mean, its not porn or anything, like myspace isnt working. u know, those kind of sites. so just please tell me why its not working.

thanks!

-danielle

We can't read minds please provide more information.

What version of Windows do you have installed?
How do you connect to the Internet, dial-up, dsl, cable?
What browser are you using, Internet Explorer, Firefox, Opera, Netscape?
Please provide links to some of the pages you are having problems accessing.
Do you have a firewall or a security suite installed? If so what firewall or security suite is it?