The first thing I'd suggest is signing out from Hotmail's built-in Messenger.
Also, in WLM, check you're not signed into any other location by clicking the drop-down menu which says your name and status. It'll say "sign out from here" as well as any other locations.
It may be worth deleting some temporary files which could be corrupt. Exit Messenger before doing so.
C:\Users\
your_username\AppData\Roaming\Microsoft\MSN Messenger\
C:\Users\
your_username\AppData\Roaming\Microsoft\Windows Live Call\
C:\Users\
your_username\AppData\Roaming\Microsoft\Windows Messenger\
C:\Users\
your_username\AppData\Local\Microsoft\Windows Live Contacts\
* C:\Users\
your_username\AppData\Local\Microsoft\Messenger\
C:\Users\
your_username\AppData\Local\Temp\MessengerCache\
C:\Users\
your_username\Contacts\
* NOTE: This folder contains your custom emoticons, display pics, backgrounds, etc. so you may want to backup before deleting.
The above file locations are for Windows Vista or 7. For more info or locations for XP, see
CookieRevised's reply to Windows Live Messenger BIG PROBLEM!.
Replace the letter C with the letter of your hard drive and your_username with the name of your Windows account.
Alternatively,
CCleaner deletes some of these temporary files/folders when you run its cleaner, may be worth a try.
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