Hi Peter.
This is a somewhat known issue that can occur with the light source materials in certain circumstances and in combination with certain other material types.
If you take the image into Photoshop normally a 'de-specle' will take care of the brightest pixels. If any remain you may have to do a little cloning or healing on those areas.
Alternatively, you can swap out the materials in your scene with alternatives, to see if this makes an improvement.
n
