sounds to me like you had a texture on, which displayed on your model. Then you hit new from polypaint and since there was no polypainting your new texture is white. This is a guess, but I bet if you turn your texture off, your model is white, disregarding any materials you have on the model. Materials dont transfer to textures unless you paint them directly in projection master.
Try this
select your model. Go under TOOL-TEXTURE- and turn off any textures.
then - Select your model. Select a color in the color palette. The make sure RGB is turned ON. Then hit COLOR-FILL OBJECT. Your object should turn colors.
Then TOOL-TEXTURE-NEW FROM POLYPAINT
and you should have a texture that is that color and has filled all the UV space.
The other thing is that sometimes objects can corrupt. Sometimes objects simply wont fill. What sometimes fixes this is cloneing, saveing, and multi-appending with subtool master.
If your tool doesnt work. Then you should try all your steps with an unwrapped polysphere and see if they work. If they do, it is your object. if they dont, then I dont know what to tell you.
ALSO- If you have LAYERS turned on, they can mess stuff up.