For some reason on my Windows XP machine. Windows Live Messenger was not letting me log in. I was getting error 80072efd. It was telling me something about not being able to load contact list. Here is what I did to solve the problem.

In Windows XP,

a.     Click Start, click Run, type cmd , and then click OK.

b.     At the command prompt, type ipconfig /flushdns , and then press ENTER. This command flushes all the DNS entries that have been cached.

c.      Try to sign in to Windows Live Messenger.