"fatal error" puzzle:

I am trying to solve this "fatal error" puzzle:
The AutoCAD 2006 user was working on a project. She had been able to
access all the sheet files which contain xrefs to all her base model
files. Sometime last Tuesday evening, whenever she opened up a sheet
file, only in this one project, CAD crashed with the message, "Fatal
error. Out of memory." I had her try a system restore thinking AutoCAD
was in conflict with a Windows update. The computer was unable to
restore the system to any checkpoint and the problem continued. I then
logged her off and logged on as administrator and installed the CAD
service pack 1 ...out of wishful thinking. I discovered however that I
could access the seemingly corrupted sheet files just fine under the
administrator profile. I created another test profile and could access
the files with that as well. All other computers in the office can open
the files. I could migrate her highly customized profile over to a new
one but I'd rather fix the existing Windows user profile. Any ideas?
Pete