What are you putting in that file?
I have my customs lisp on it.
So when I make a LISP to send outside my enviroment, the lisp I send could need a defun that is just load by the my ACAD2008DOC , and i can not test it on my own ACAD.
FYI
ObjectARX 2008\docs\arxiop ->Proper Use of Support Files->Follow Guidelines for Modifying Support Files
The same like said rkmcswain :
XML-based files (i.e., .atc, .aws)
Do not modify directly. Modification of these files, or other XML-based files in AutoCAD, is not recommended because they are based upon an XML schema that can change at any time. Modification and/or customization should be performed through use of the documented APIs related to the feature the files represent.
.dst (sheet set files)
Do not modify directly. Modification and/or customization should be performed through use of the documented APIs.
acad.mnl
Do not modify.
acad.cui
Do not replace. Modify only using the CUI APIs. Add your UI components using partial CUI files whenever possible. This makes it easy to remove your UI elements if your application is uninstalled. Modifications to the user's main CUI file is allowed using the CUI APIs but should only be used to add a partial file to the list of CUI files to be loaded.
acad2008.lsp and acad2008doc.lsp
Do not modify.
template (.dwt) files
Do not overwrite any template file, such as acad.dwt. If necessary, use a drawing template file to establish your application's drawing environment.
help files (.chm)
Do not replace. Implement your own help files instead.
acad.lin and acadiso.lin
Do not modify or replace. Supplying additional LINETYPE files is fine.
etc. etc.
~'J'~