You talk about "rotating one click", which suggests to me that you're using the knob. There are known problems using the knob to adjust the dimmer, as they are controlled by the same PIC. If the problem goes away when you use the remote control, this is what you're seeing.
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Toby Speight
030103016 (80GB Mk2a, blue)
030102806 (0GB Mk2a, blue)