>Check that you have connected the common pin of the ULN2003B to your
>*relay* positive feed, this will enable the free wheeling diode circuits
>when relays are de energised.


One product I know of drives thermal printheads with this chip (resistive
load) so they connect the printhead common to +9V and connect the diode pin
to +5V.  This results in the 5V regulator being shut off most of the time,
and the +5V line being at 5.24V.  Funny thing, they have a lot of
unexplained crashes.