Like Phil, defrost - microwave - pan, much nicer than just microwaving.
Sometimes I fry some more onions (a bit of garlic, chilli and pepper sometimes too) in the pan too before adding the curry, and I also rinse the container out with a little boiling water and add it to the pan.
Now not sure what Natterjack is doing to overcook everything

, but, If the pan is hot, it should only take a couple of mins at most to reheat.
Martin