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From the Safari Menu Bar click Safari/Preferences then select the Security tab.
Click: Show Cookies. Delete all Twitter and Facebook cookies. Relaunch Safari.
If you still have problems accessing either site, open Keychain Access (Applications/Utilities) Select Passwords on the left. Delete the Twitter and Facebook keychains. Relaunch Safari and try logging into one of those sites. If you still have problems, delete the, "Safari Forms Autofill" keychain. Relaunch Safari.
I get redirected to sites like MySpace.
Many Safari users (including myself) benefit from using Open DNS Free / Basic to avoid redirects.
Not that I can for see. Basically a dns server is a big phone book that routes you to the website your looking for. So if you type in google.com the dns tells your browser where to actually go. So it doesn't matter what dns you're using as long as it works.
From Wikipedia "A Domain Name Service resolves queries for these names into IP addresses for the purpose of locating computer services and devices worldwide."
This seems to work only I'm not sure if there is any risk in doing this?
I don't know why you think this could be a security risk.
I use NameBench to find the fastest name servers and Google servers are normally the fastest. If I remember correctly 188.8.131.52 is fast - not their fastest but it is easy to remember.
I have my own name server but it refers to one of the fast Google name servers for domains it does not know.