Ok, so this has happened to me often, but ALWAYS in the same locations.
I used to drive on Skyline (Hwy 35) from Hwy 92 to Hwy 9 on the San Francisco Penninsula on my way to and from work.
When I arrived at a certain location, my laser alert would always go off for a few seconds. I noticed it was in a treeless clearing, where I could see down the mountain, overlooking Stanford University, and Interstate 280.
This is also the location of Stanford's large radiotelescope. I don't know if that had anything to do with it, seems not since laser is "light" (and the radio telescope just scoops up signals - does not transmit them). The road itself is usually empty, and no cops would waste their time doing traffic there since only 1 car goes by every 10 minutes - also there is nowhere for them to hide - no turnouts or anything. (Not to mention the poison oak they would have to be standing in)
I also noticed this when I drive just North of Las Vegas, near Nellis AFB. There is a certain spot on the road where it goes off. Always the same spot.....
Any ideas as to what is flagging these alerts? I have no clue. It does not happen in very many places, but when it does, it seems to be out in the boon-docks, but always repeats when I pass the same spot on another trip.