ah, this problem ive had myself,
its a very difficult one many end up redoing there whole system over it,
but these steps should work
1. uninstall it (get rid of both windows live messenger then windows live essentials
2. hit control alt delete and open task manager
3. go to file, new process
4. type in regedit this opens your systems registry, which at times leaves traces of programs u uninstalled yes its very frustrating.
5. open HKEY_CURRENT_USER then to SOFTWARE
6. go to microsoft
7.go to windows live folder
8. delete messenger folder.
9.now close KEY CURRENT USER and go to HKEY_LOCAL_MACHINE and go to software there
10.Repeat steps 6-8
11. close regedit
12. reboot
13. redownload a fresh copy of windows live messenger (i perfer using filehippo.com for it, best download site for that. heres the link http://www.filehippo.com/download_msn_messenger/
14. install it
15. if problems persist you may wanna contact microsoft about the issue.
if this helped, im glad, if this worked for you feel free to add my msn and let me know your happy it works, i love hearing from people, foreverbry@gmail.com
Goodluck i hope this helps