I suspect that a panel GFCI or arrestor would probably not make a great
deal of difference - sounds more to me like a grounding problem. John's
suggestion of thoroughly checking the grounding system out and/or replacing
the GFCI with a new one is more likely to bear fruit.

I'll note in passing that electrical codes don't require GFCI's on freezers,
but that assumes it's on a dedicated single outlet circuit.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

You might want to reconsider having GFCI's on your freezer and sump
pump circuits. The theory is that you want to avoid nuisance tripping
on something that could really cause a problem if the power cuts out
on these circuits. Since lightning is a problem for you... I would
consider the highest qualitity surge protection for these individual
devices and perhaps a whole house surge protector.

If you live on the highest hill in the area, lightning theory suggest
that the downward streamers prior to a lightning stroke will seek out
attractive elevated conductive features on your property (antennas,
gutters, chimney flashings, vent pipes, and so forth..) This would be
in preference so similar features at a lower elevation. It is all
based on probability, however, and the fact that you live in a
lightning prone area suggests that additional mitigation steps would
be worthwhile.

Beachcomber