One thing i forgot to mention.  The layout is wired for both DCC and DC.  Switching to DC on block 1 makes things work fine.  I've also tried 2 different controllers - a Digitrax DC52 and Bachmann EZ, and the results are identical.

I have a small (4'x6') n scale layout divided into 3 electrical blocks.   When I try to run my Bachmann GG-1 DCC on block 1, the headlights flash indicating a short circuit. On the other 2 blocks it works fine.  Every other loco I have - both Bachmann (1 steam), Kato (GG-1 and EM diesels) and BLI (steam) work fine.  The short appears to be detected once the GG-1 crosses a siding turnout on to the main line.  Any idea how to fully diagnose this or is it simply an idiosyncrasy of the DCC decoder in Bachmann's GG-1?