uploaded service pack 1 for autocad 2012 last week and now all plots come out in light blue lines. Have tried everything from changing line colors, changing plot styles in the table editor and still same blue lines. Anyone else having this problem and if so how do we correct???

No problem here.  I installed the update as soon as it came out and it did not affect plotting.  What printer/plotter are you using?  Did you change drivers for it recently?  Maybe it is a Windows update that fouled things up.

using hp design jet 500 and have not updated drivers since getting new computer a few months ago. With windows 7. Was plotting great but now nothing but blue..

Coincidence?  I'm using a HP DesignJet 500+ on a system running Windows 7 64-bit.So even if you select a monochrome.ctb or stb everything plots in blue?Have you checked the ctb or stb plot style file you're using?

yes

even downloaded my old grayscale ctb from older version 2008 auto cad and still have the same problem

And you have uninstalled and reinstalled the plotter?

have not done anything with the plotter....

for those of you who tried to help, thank you. I have determined after talking with some folks to replace the print head on the black ink side.. this should do it...hopefully....