[Mr B]

You guys might also try hand pollinating the squash. They might not be getting pollinated well enough.
Take the "male" flower (the one with the long stem) and tear off the petals to expose the Stamen. Then open the female flower (the one on the end of the small zicchini, squash, pumpkin etc. and rub the Male Stamen all over the female Pistil. This will insure good polination and help with fruit reaching maturity.