im not an expert at computers but im hoping someone can help me with a problum i have. . .

ok well i use IE and i get restricted from alot of sitez ::for example:: i cant sign up for almost anything it will let me go to the website but if i click sign up it will say "the page cannot be displayed" but yet i can sign up for yahoo and a few other things so far the sites that i have tryed to sign up for and they dont work were sub domain sites. . .i also tryed to sign up for a new aim name. . .and a message board for my site. . .and it just didnt let me. . . ive tryed to restore the defaults on my internet options and it doesnt work i also tryed the Per Site Privacy Actions and that didnt work ether does anyone know a way i can fix this problum? or at least let me no what is wrong???