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DNS changes normally take a maximum of up to 72 hours to resolve. Unless there is an error in the IP addresses given (highly unlikely), I don't see what could be the problem.
Make certain that your account at the company hosting your web site is alive and active.
Apart from that, I don't see what could be the delay.
We've done 4 DNS changes here this week for clients and the most it took was 48 hours. One even was done the same day, wich is not something we are used to seeing every day!
Did anybody else on WW experienced problems or delays lately?