Still can't plot grey scale on HP1050 & HP 5000 (updated)

I'm running 2000 on an XP Pro SP2 system plotting to a HP 1050 (still using
factory settings) and occasionally when I plot the drawing will show in the
preview that the appropriate lines will be screened. However when it is sent
to the plotter all lines plot in solid black. Now when I try the sameting on
another computer using ACAD '02 it plots fine. I have tried installing the
updates for 2000 also. But no luck in fixing it. I'd appreciate any feedback
on this.

Thanks

Updated

I tried plotting on an HP Laserject 5000 also and I can get the preview to
show the drawing as being screened. However the final output is still solid
black. I've tried the following:
Reinstalling the drivers for both printers
Using different ctb files
Rechecking the settings after the preview. And yes on occasion Autocad will
revert to none.
Also I've tried going into file>page set-up and applying the changes there.
This way seems to keep the settings to the correct ctb and printer. However
does not fix the screening problem.

Again I would appreciate any input.

 

Everything still look the same. In fact I tried using 2004 to plot the same
drawings and that seems to plot fine.

 

Yes, I have installed it.