Fist of all, did this fireplace receive the repair kit from the Twilight recall? Should be a sticker down in the valve compartment.
You should have the Fp wired to either a wall control or remote but not both.
You need a pro to check the items discussed by fire-parts and others. If this is LP, it is simply a design defect--the LP regs. tend not to turn down.
Contact HG Tech support first with your model # to get it into their system and see if it was in the recall.