[markem]

I haven't seen it, but a couple of suggestions.

1. When it happens, see if you can video it for documentation.
2. Check the load on the power circuit. Move items off the circuit or check the load if you know how.
3. If you happen to have any amateur radio users in the neighborhood, try checking with them to see if you can line up the glitching with their use. It is the responsibility of Sharp (and thus you) to not interfere with the radio signals, per FCC rules.
4. Go to Home Depot (or whatever) and get a power adapter for your plug. Or you can do like I do and get a conditioning line filter.

I use this power strip for my electronics - expensive but works amazingly well:
MFJ AC Line RFI Filter Model MFJ-1164B