cd-rom image simulation

i was bored so i went to install nfs, but when i restarted to play the game it wouldnt load. kept saying insert game cd, but it was in. i went to my computer and it showed me having two cd-roms, eventhough i only have one. under device manager, the fake cd-rom says image simulation. i delete it, but when i restart, its still there. how do i get rid of it, and what caused it?