General solution tot his question is find it with 'search', (you'll
probably need to turn searching hidden and system files, and subfolders,
all on), right click the file, select properties, and see what it has to
say for itself. If you don't like what you see, rename it and see if
anything breaks.
In this case, googling (
www.google.com) for 'loader.exe' will reveal
that it is probably spyware/browser hijacker, so you have not been
running your virus scanner and spyware remover like you ought to.
www.security.kolla.de for spybot S&D,
virus checker of your choice (but =get one= and keep it updated, or you
are a public menace).