problem in printer interface

Hi,
I have a problem with printer interface.
I connected the printer to the instrument through parallel port.
After the completion of the operation in the instrument, if I switch OFF the instrument without switching OFF the printer and keep the printer in ON condition, then after switch ON the inst. for the next time, a garbage data is printing automatically.
the strobe line is kept HIGH in default condition.

Pls, suggest the solution.


Shaaaaa..