plotter problem

We have a problem printing inserted tiff images, they print totally black.
We tried inverting the image , does the same thing. Funny thing though
the tiff's print just fine to a cheap lexmark printer. Out plotter sales
tech support was at out location yesterday trying some new plotter
drivers and other things. He is very good and has solved all of our
problems except this one.
Anyhow after he left, all of a sudden we can't seem to get our border
lines on the paper, it's like all of our prints are set to extents. But we
checked the plotter settings and they are still set to "window". We don't
use paper space, but rather print straight out at set scales.
Does anyone know what might be the problem ? It may be days before
our technician can make it back into our town.
Appreciate any info.