Ah, ok it's one of many 'pretend cd' programs
You can use it to load cue/iso etc and the pc sees it as if you had actually got an extra cd drive and sees cue/wav or iso files as a 'real' cd
You can get it from here
http://www.free-downloads.net/programs/Daemon_Tools(I'd recommend unticking the free google toolbar or whatever they call it now - you don't need it)
The real name for it is a 'cd emulator' - google it it you want more info
The main feature of them is that you can use a disc image on a hard drive as a 'real' cd just as if you had put a physical cd into the pc
Say you have one hard drive called 'C:', a dvd/cd called 'D:' then after installing daemon tools or a similar program you'll get an extra dvd/cd drive called 'E:'
It's not a 'real' drive but just a pretend one that you cad use to load .iso, .cue file etc and the pc thinks they are 'real' cd's and you can use for example a cue/wav as if you had put a real cd into the pc
(Sorry for the vague descriptions but i'm in the UK and we're getting all ready for the monday night nfl -by the time it starts I don't think anyone will be sober enogh to watch it though.....)