Check your document settings.

Also, try going to the material room and moving the transparency up or down and putting it back to where it was.  When things go invisible in Poser 6, the transparency trick sometimes helps.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi