Since when have you had this problem?
Can you think of anything that may have caused it?
If you've installed add-ons such as SweetIM or SmileyCentral, these could cause problems.
Try reinstalling Windows Live Messenger.
1. Go to Control Panel > Uninstall Programs > Right click Windows Live Essentials and click Uninstall/Change > Follow the instructions to remove Messenger.
2. (Optional) Restart computer.
3. Download and install
Windows Live Messenger again.