I had some problems with the  PowerEdge 1600SC and ACPI last August.
   If I recall correctly ACPI would free - but still access some
   memory. I recall that I did something ugly to make it work - but
   did not have the time to look for the root cause.
   If this problem still persists I can dig out the patch.
   ( To serve as a starting point for hunting the bug )

i *think* these problems are fixed in newer ACPI-CA releases we
are now using...