I don't know if this problem is idiosyncratic, but maybe the collective wisdom of the forum can help:
I have a DX Ultrafire light on my bike, and it only has (officially) two settings: on and off.
But when it is on, it seems to alternate between on (high) and DIM...and the DIM is quite dim, I would estimate less than half as bright as the normal/high setting.
It seems to randomly jump between high and dim...not related to when I turn it on/off....not related to whether I am using fresh or older batteries, and it happens with both disposable AAs and rechargables.
I am not pleased with this situation as the light seems to spend most of its time "dim" and its usefulness when dim is really marginal.
Anyone else experience this problem, or any suggestions?