MSN contact list is full

When trying to add a new contact to your list MSN Messenger tells you that your contact list is full.

MSN Messenger currently has a limit of 150 contacts. If you have 150 contacts in your list there is simply no way to add more new contacts. This amount might be increased in the future. In march it was increased from 100 to 150.
If you have an amount of contacts that is below the maximum amount and yet, you are not able to add a new one, this is most likely a server side issue that may show up after adding and deleting contacts for some time. Usually, this problem fixes itself after some time.
When you really need over 150 contacts or are not able to add new contacts the only thing you can do for now is to create one or more extra MSN Messenger accounts. Using a so called "polygamy patch" or a client like Trillian you can be signed in with more then one account at the same time.