Apparently Osm2go has a problem with relations. When I joined some parts of a way, turning them into one way, and thus deleting the others it tried to upload relations with lots of empty tags.

I ended up having to fire up my work laptop, and use Potlatch to delete those road parts (As I mentioned in a previous diary entry, Potlatch makes Flash crash on my Linux PC).

On the positive side, once I deleted those road parts in Potlatch, and had Osm2go download the data again, everything seems to be working again. Phew.

(The fixed map hasn't been rendered yet, though).