AUTO/MANUAL Calculate in Excel when opening *.slk files
 

I'm going a little crazy with Excel today. I am attempting to write
a macro that will allow a user to open two additional spreadsheets
(*.slk files) generated by the same external utility. I have a very
complicated worksheet that analyzes the data from these worksheets.
As such I have made sure that the main workbook has calculate set to
MANUAL. When I open the first *.slk file and copy the needed data
and paste the data everything works fine (i.e. NO CALCULATIONS).
However,when I load the second file this *.slk file opens and
immediately performs a calculate which takes several minutes. Both
*.slk files were created by the saming utility (external to Excel) and
both are opened from the same function call. I also found that when I
switch the order that I open the files that calculation also reverse
meaning that the calulations are performed by the first file
(formerly second) opened and not the second file. This leads me to
believe that there is something file specific not code related. Any
ideas?

Thanks!