I can't get Windows Live Messenger to open

Hi, I just got this new compter with Vista and have been trying to load
Windows Messenger. It has loaded and the icon is on my desktop, however, it
won't open.

A window comes up that says Messenger has stopped working and when I ask it
to tell me what's wrong, it tells me it is the Data Execution Prevention
stopping it.

I tried to change the settings using the Windows help & support. However,
when I try to add Windows Live Messenger to the exception list, it says it
can't find the program. How do I fix this as it is a Windows program and my
Windows Vista is preventing it from running?

Thank you for any help you can give me.