If your msn refuses to sign in...

A temporary fix is to paste:
65.54.239.80 messenger.hotmail.com
65.54.239.80 dp.msnmessenger.akadns.net

Into a file known as hosts. It's found in C:\\Windows\System32\Drivers\etc. Open with notepad.

The file looks something like:

# Copyright (c) 1993-1999 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host

127.0.0.1 localhost

Just add in the above mentioned stuff under the line 127.0.0.1 localhost. And hopefully it works =)