LED Under Cabinet Lighting
Do you possibly have the wrong power supply connected to the lights? Usually its low voltage 12 volts, but maybe these require 24 volts?
Usually you can go from a halogen or xenon bulb to an LED insert, but I don't think you can change from LED to a traditional halogen or xenon bulb. Wiring should probably be ok to chang out the lights to something else, what gauge wire was used to connect the lights up with? I probably wouldnt go any smaller than 14 or 16 gauge wire.
My undercabinet lights I routed 4 runs of 14 gauge wire to all my lights and to the cabinet under the sink where the transformer(s) will sit. I think to start out with I will be running 5 10-watt bulbs, but with the ability to upgrade to more lights or change out to 20 watt bulbs if I need to.