Why are ID's suddenly showing on my messenger instead of real names?

My Yahoo Messenger 10 only displays IDs but not Full names or Nicknames. How do I fix this?

• After installing Windows 7 Ultimate x64 on my PC, I was a bit surprised to see that my Yahoo Messenger list was only showing IDs, instead of Nicknames or Full names. I checked the File/Preferences/Appearance setting and the "Nickname and First or Last name" radio button was checked. I tried re-installing it, but it still doesn't work. It's very annoying and frustrating! If I try to see the Contact details for an ID, they're empty and if I try to update them with a Nickname, I get an error: An error occurred while trying to save to server. What the heck is going on?! I thought maybe it would go away by itself, but I've had this problem since yesterday and since then I rebooted the PC, hence Yahoo Messenger, a lot of times. Anyone knows what I should do?!

• Answer:

  Hang fire on this one - the Yahoo server is up the creek and lots of similar problems with internal emails - - Contact Lists etc. I expect a shutdown soon to rectify a lot of these problems - but don't hold your breath. I see someone meticulously changed the format back and the next time they signed in it had reverted to Usernames.