OK, so it really seems to be a C700 specific problem. I don't think it's tightly connected to matchbox. This instability can be caused by a wrong C700 kernel or some misbehavior because of the partition sizes.
I ask the dev team: have you got it working on a C700 or we are alone with our problem? The bug can be narrowed because the hardware doesn't differs much from the other C models. I hope you have some solution or idea for us, poor C700 users.
Zumi