Display picture won't change.

When I change my display picture in my messenger, I see a new picture in my
IM box, but others see a different picture. Also, the picture doesn't change
in the sign on window. Basically, the only place the picture changes is my IM
box and at the top of my buddy list.

I have tried having the computer 'forget me' but it reverts back to the old
picture when I want the computer to remember my screenname.

Any ideas what I can do aside from reinstalling?

Thank

Thanks