For some reason since the last time I went of LFS (about 2 weeks ago) the F4 button which usually changes the display from fullscreen to a window is now minimizing LFS and opening Powerpoint. I'm totally clueless why it should do this and how to stop it. Help

The Command to window LFS is Shift+F4.

You probably have Powerpoint mapped to F4 in your Keyboard Software.

Figured it out, theres a little button on my keyboard that changes the way the function keys work, I must have caught it by accident.