I have defined a couple of functions in a XLA file. I've registered it
through the Tools - add-ins dialog. I can successfully enter formulas in
cells which call my functions. If I save the workbook and exit from Excel,
and then reopen the workbook everything works as correctly.

So far so good...

The problem occurs when I save the xls file to a DAV repository and then
access it from IE. When Excel is launched the path to the XLA file is not
correct so the functions do not work.

The XLA file is installed on c:\program files\... When Excel is launched
from IE the path to the XLA file is set to the drive that my profile is on.
If I update links and point the XLA bcak to C: the functions work properly.

I've looked at the contents of the XLS file, and I see the path to the XLA
file is stored in there without a drive identifier. How does Excel determine
which drive to add to the path to the XLA file? How can I control this
behavior?

Thanks,