Hello!!
We are rendering with photon map with skylight portals and
irradiance map. In some images we are getting a stranger noise,
in areas lit by direct light. The irradiance map is used just in
the first bounce after the photon map is loaded.
The stranger thing is that the noise apear in the photon map too. 
Here is the image
http://leo.bartz.vilabol.uol.com.br/Noise.htm
Thanks!