I logged in to Windows Live Messenger this morning to find that all of the people on my Coworkers group (a group that is built into Windows Live Messenger) had disappeared!
At first I thought possibly that I had been fired, but fortunately that is not the case.
Microsoft simply lost all of my data. This shouldn't surprise me because as I contractor I had to reconstruct all of the MSN internal InfoPath help desk forms from screen shots because they somehow managed to lose that data.
The lesson learned here is to keep a seperate copy of all your IM contacts on your local PC. You will need that list if Microsoft loses your IM data, as Microsoft obviously has lost for me.