Data Execution Prevent & Windows Live Messenger

Well I just bought this computer two days ago and it's operating system is
Windows Vista Home Premium. When I try to sign on to Windows Live Messenger a
screen pops up saying, "Messenger has stopped working". Then underneath it it
says, "A problem caused the program to stop working correctly. Windows will
close the program and notify you if a solution is available." Then I click
"Cancel". After I click "Cancel", a bubble pops up at the bottom of the
screen that says, "Messenger has closed" and "To help protect your computer,
Data Execution Prevention has closed messenger. Click to learn more". What do
I do about this? Everytime I try to log in to messenger or do anything on
messenger this happens!