What renderer are you using?
I believe this may be NIM040765. If you change <all other values> in the renderer to some color, I bet your white "holes" will display using this color.
Very frustrating that this bug has still not been addressed as of ArcGIS 10 SP3! Note that the problem occurs when you have pyramids and you map one of the fields from the Raster Attribute Table (not when you map the value itself)...