Jeff,
We are also having that problem. When we experience that error, ADT also places the xref block in paperspace full scale, and corruptes the PS block so that we need a full recovery and resave. Worst case we needed to dump our sheet file and recreate it from the original base file.
We feel the cause of this is hatching using the hatch boundry to ADT objects like elevations sections, then xrefing that drawing into another. We have found that hatching to a pline on a non-plotting layer prevents those errors from happening. Although it may seem that drawing a pline for all hatches is time consuming it really saves time when the elevations/sections update. We just stretch the pline around a little and the hatch is fixed. We have also noticed fewer crashes when we hatch that way.
I would like to see if anybody else has had similar problems or if Adesk know the problem.
Chris H
Gabbert Architects Planners