If you are receiving error 8e5e05f6 when you try to sign in to Windows Live Messenger 2009, please try the following:

1. Enable Hidden Files and Folders

1a. Windows XP

1. Click Start, My Computer.
2. Choose Tools, Folder options.
3. Switch to the View tab, find Advanced settings.
4. Check the option Show Hidden files and folders.
5. Clear the option Hide protected operating system files.
6. Clear the option Hide file extensions for know file types check box.
7. Click OK and close the window.

1b. Windows 7/Vista

1. Click Start, Computer.
2. In the Explorer window, click Organize, Folder and Search Options.
3. Switch to the View tab, and check the option Show hidden files and folders.
4. Click OK and close the window.

2. Delete Windows Live Contacts folder

1. Click Start; double click on [My] computer.
2. Browse to the location
   Windows XP:
   C:\Documents and Settings\<Your Windows logon name>\Local settings\Application Data\Microsoft
   Windows 7/Vista:
   C:\Users\<Your Windows logon name>\App Data\Local\Microsoft
3. Delete the folder Windows Live Contacts completely.
   Note: Ensure to exit Windows Live Messenger (msnmsgr.exe; wlcomm.exe) from the Task Manager before deleting the Windows Live Contacts folder, otherwise you will get an error prompting that you can’t delete the folder.
4. Try signing in to Windows Live Messenger.

Source: http://messenger-support.spaces.live.com/blog/cns!8B3F39C76A8B853F!15127.entry