Why is Add-In path associated with save location
 

Using Excel 2003 with an Add-In I created. Here is the behavior I am trying
to understand. The Add-In is located in the Microsoft Add-Ins folder under My
Documents. I create a workbook and save it to drive C (CreatedOnDriveC.xls).
I create another workbook and save it to drive F (CreatedOnDriveF.xls). Both
workbooks use functions from the Add-In. I now copy the workbook created on
drive C to drive F and copy the workbook created on drive F to drive C. Each
drive now contains copies of both files. I can open both files from drive C
and they update properly. I can open the file created on drive F from drive F
and it updates properly. The problem arises when I open the file created on
drive C and then copied to drive F from drive F. When I try to open
CreatedOnDriveC.xls from its location on drive F, I get the update links
message. The problem is that the links now refer to a path on drive F that
does not exist (F:\....\AddIn.xla!FunctionName()). The path is correct except
for the drive letter. Why would Excel change the drive reference when it
knows where the Add-In is installed? This is confusing because Excel had no
problem opening the drive F file from it location on drive C.