parts of plot disappear

we have a re-occurring problem with portions of a plot not reflecting what is shown on the screen.

the drawing looks fine on the screen, but when doing a plot preview parts are missing and the final plot has the same parts gone too. I have checked the "no-plot" toggle, the layers are correct and when the drawing is opened there are no errors shown nor is a recovery requested.

if we do an audit of the drawing, the problem disappears and the drawing will plot normally. this is the case even if audit reports no errors. this happens on all the workstations and with drawings that are coming from several different people. they have the same software and the same addons. it does not happen in every drawing. it appears very random.

we are using LDT4 with the civil package.

i'm at a loss, i cannot re-create the problem, no new lisp routines have been added (or macros). it not like it's a life or death problem, audit always fixes it, but it does concern me. Any body got any idea what might be happening?