Suddenly Can't Access Password Sites

Hello,

I've never had this problem before, and I don't know what's going on. The internet works fine, except for the fact that I cannot access websites that require a password like Facebook. I can access Yahoo, but as soon as I try to sign in to check email, I get the same page. It says "Problem Loading Page, the connection has timed out." I tried to download Google Chrome, but it won't let me download anything either. All non-password sites work normally.

I am using Firefox, but I've tried these sites in Internet Explorer and same results. I did a system restore but that didn't work. I thought it might be the Firewall, so I disabled the Firewall temporarily but that didn't make any difference (so I turned it back on).

I do use a wireless router, but I unplugged it and just used the modem, but that made no difference either.

Any ideas?