*Back up all your emails following this tutorial and an additional link.
Windows Live Mail - Export and Import Email Messages How do I import and export email, contacts, and calendars with Windows Live Mail? - Import Email Messages or Back Up and Restore Windows Live Mail
*Download and install Revo uninstaller and uninstall all components of Windows Live in Advance Mode. Do not reboot if you are prompted, ignore it and continue till the page it brings up the remaining registries. Select them and delete them then Reboot. Revo Uninstaller Pro - Uninstall Software, Remove Programs easily, Forced Uninstall
*Download a fresh copy of windows live essentials from the link below. (Install only windows live mail if that's all you need) Download Windows Live Messenger 2011 (15.4.3555) - FileHippo.com
Do the above and post back for further suggestions.