Saturn fans.com states the problem is with the alternator voltage regulator. Unfortunately, this problem has not been openly admitted as a fault of the l200 series, even though many owners have this intermittent flash of the lights. A technician I know said this problem has to do with the "comfort control module" which operates 12v devices like door locks lights security ect. My l200 has this flashing and about the time when the flashing got worse, the keyless locking mechanism was almost inoperable. So..... logically this problem has to do with a combination of both comfort control module and voltage regulator. The flashing is possibly the ccm whereas it could be a voltage spike due to improper voltage regulation, then it may be the alternator. Best to have a Saturn dealer check the prob. but ask them to document any tests of your alternator.
I had same problem with a 2001 L200. I heard a clicking sound inside the engine fuse box and it coincided with the lights blinking. Found it was one of the relays inside inside the fuse box. Replaced the relay that seemed to be clicking and the blinking light problem stopped.