Try uninstalling the one you have and try using an older version. Try msn messenger 7.5 if you can and see what happens. When you install it, it will probably say there is a newer version. Just hit no and continue using it and see if it works.
Here is the link:
http://files3.download3000.com/downl..._Messenger.exe
OR
You could do a system restore.
1. Go to Start, click Run. Type "
msconfig" and hit enter. (type it without the quotes)
2. On the General tab, click the "
Launch System Restore" button at the bottom.
3. A new window pops up. Make sure "
Restore my computer to an earlier time" is selected, and hit next.
4. In this window, you will see a calender. You will also see some numbers that are darker than others. Those are the restore points that you can use. Try to remember the date this started happening and then find a date that has a restore point thats closest to the date the problem started. For example, if this started on the 10th, try to look for a restore point that closest to the 10th. Once you figure out which date you want to use, click it and then click next.
5. At this point, make sure everything is saved because your PC will restart after you hit next again.
Thats it. Hopefully that should do it. By the way, here is an example of what I mean in step number 4:
http://upload.wikimedia.org/wikipedi...em_Restore.png. See how 17, 18, and 19 are dark? Those are the restore points that I'm talking about.