I've been working on a project today that I first started playing around with a couple of weeks.  Previously I have been able to render still images with no problem but today for no particular reason (as far as my brain can tell) after the indirect lighting calculation I'm left with little white dots all over my background prop and what has the appearance of a solid wall of mist in the midground to the background on my scene.  I've tried reseting render settings to default and the classic switching my computer off and on again but the problem still persists.  Any help and advice would be much appriciated.

Poser Pro 2012

Windows 7 Profesional

Intel i7 2600 8MB

16GB ram DDR3

Gigabyte Geforce GTX 550 TI OC