Windows Live Messenger 2009 Options

I've been trying to change my display name by opening 'Options' and every single time I do this, I get a pop up that says Windows Live Messenger has stopped working.
I have uninstalled and reinstalled and still had the same problem!
I cannot change my display name, or change any settings (like, I do not want alert sounds).

Is there a reason for this?
It's getting really annoying and I can't install a older version because, once again, it makes me download version 9 whether I like it or not.

Configuration: Windows Vista
Internet Explorer 8.0

I installed it in March, and my computer won't restore that far back, but that is the last time it worked without issues.