Re-install is the only way , and you might re-download if the setup has been changed or corrupted,
And do you know anything like did you change it manually or it happened without your knowledge,
Scan your PC in case there is a virus make sure the antivirus doesn't flag crossfire as a virus if it does disable it and if you did it then its your fault always make a
backup if you just want to open it or change it .
Hope this helps