"Incorrect structure found in PDF file"



I put together 40 to 50 page seminar presentations by applying the
Acrobat "Create PDF from Multiple Files" command to the same number of
individual PDFs acquired elsewhere or generated by Mathematica or
Illustrator, then reorganizing these pages in Acrobat.

Fairly often, when I try to Delete an unwanted one these pages using the
Document >> Delete Pages menu command in Acrobat I get the error message
"An incorrect structure was found in the PDF file", and the page simply
refuses to delete (workaround is then to move it to the end of the file.

Is there any way to cure or avoid these problems? Or a diagnostic I
could run on the errant document

--Burst (Extract) the file back to individual pages, run each individual
page through a Save or Save As process in Acrobat or Illustrator?

--Do the preceding on every page before assembling the first time?

--Buy a whole new suite of Adobe programs?

--?????????????

Doing a Save or Save As on the complete file doesn't seem to help.

[This happen on a MacBook running Tiger (OS 10.4), Acrobat 7.0 Standard,
Illustrator CS 7.0. Send me an email; I'll forward a cc of one of these
files.]
.