Since version 11 when printing sometimes the pen tables change to the same width. The saved pentable file also changes or doesnt load properly. I tried setting the saved pentable file read only but datacad crashed.
Do you have your custom Pen Table loaded into your default drawing? Have you saved your custom Pen Table(s) as new files, or are you using the default name (DcadWin.DPF)?
There is an issue with the Pen Tables (that I think should be changed) and that is: you need to do a Save As before you make any changes to the Pen Table, since any changes you might make get saved -- even if you don't do a manual save.
Are you using the Plot Preview -- if not, you should, and this will prevent any "bad" plots. Also, I have Alt-P set up to open the Pen Table, so I can check it before I plot.