Okay I found this on another forum.. it may work.
Right click the iso file and select 'open with', find 'Disc copy' in the new window and press ok. That should allow you to burn the iso.
If that doesn't work I suggest you download
ImgBurn instead, its free and easy to use.
Just install it, right click the iso file and select 'Burn using ImgBurn'. In the new window that pops up press the button in the bottom left corner.