I understand that being in prison should not automatically disqualify your right to participate in the legal system, but the abuses from those with far too much time on their hands make the disqualification idea might tempting. It would spare the courts lawsuits like this one:

In one suit, an inmate who apparently asked how many pork chops he would be allowed to eat was told he could eat all he wanted. He did and when he became sick, he filed suit against the state.

I have no idea how you fix this problem, but every failed suit costs you and I money...not to mention the expense from the (hopefully) rare victories.