I've been getting it too, occasionaĺy. Sometimes,I can go down to 30% hull with no problems, other times, my hull is at 90%, but every time I use my pulse lasers for more than a short burst, they malfunction. As well as not shooting when they should, they carry on shooting randomly afterwards, which is really dangerous in a high RES. The only option is to go back for repairs.
This change seems to have come very recenty. I've been using the same ship in the same place for about a month and it didn't happen before.
I always set my ship back to 100% integrity when I go back to the station. I did get random module malfunctions in another ship several months ago, but that one was right down to about 30% integrity, so it's always worth checking that.