How To:
1. First of all close all instances of Windows Live Messenger, then Open Windows Explorer and browse to the folder: %AppData%\Local\Microsoft or C:\Users\AppData\Local\Microsoft
Its hidden folder location, so you may need to enable show hidden and system files. To do so, just follow it.
•In Windows Explorer, Click on the Organize menu, click Folder and Search Options.
•Go to View tab and in the Advanced settings list, select Show hidden files, folders and drives under Hidden Files and Folders.
•Finally click on OK or Apply button to commit changes.
2. Find the folder named Windows Live Contacts and delete it.
3. Now relaunch Windows Live Messenger and sign in, you won’t see those false invitation anymore.