In the end I did a master reset. It seems to have fixed it. I had to redo the tuner and change video output back to svideo. It's fine for the moment. Just wondering if anyone who owns this type of PVR has seen this happen.
Stutter replay happens to me on a regular basis. I can solve it by simply switching off the pvr (from the power button on the remote, not at the wall) and switching back on. This means I do not have to a factory reset. Give it a go and see if it works for you.