reset microcontroller
You may need to separate grounds for dspic and the power stage. They need to be connected at one point, like a sense resistor if you have it. Also, adding a ferrite bead in series with dspic ground may help, as well as another one on the input of the linear regulator.

Also, some dspics have a register which contains a cause of the last reset. You may want to find the name of this register in the datasheet of your dspic and check its contents to see if a reset was due to MCLR line or BOR or something else.