A few weeks ago I installed the new Live Messenger Beta (part of the Live Essentials pack) and started working with it.
Just now I got a very irritating error “800c013a” when trying to sign in.
Here comes the resolution to this problem:
1) Make sure that both the msnmsgr.exe process and the wlcomm.exe process are not running.
*) Goto Task Manager.
*) Goto the Process tab.
*) Right-click on both the msnmsgr.exe and the wlcomm.exe process and select “end process”.
2) Delete the Live Messenger’s Contact Store
*) Goto “c:\users\%username%\AppData\Local\Microsoft\Windows Live\Contacts” and delete the folder which has the name of your e-mail address.
*) Restart Live Messenger and sing in.