I have the S770 and its reliable. I also have the older Z1000, EX-P505, and newer FH100 and FH20. And more with family members. I think V8 too.
They've all been solid. The Casio G shock camera has documented failures, however. Ironically, its probably the least reliable casio camera. If you check the Amazon reviews, its prone to failure.
Generally I'd consider Casio top tier in reliability, with very few "duds" in terms of their model line up. Unfortunately, you've just been unlucky. On the plus side, Casio America's support is fast and cheap. Try their service center in NJ.