Excel Add-in prevents a workbook from opening when doubled clicked

[Mike Sealock]

I created an excel add-in (.xla) and loaded it via tools
add-in and now when I double click on any workbook from
the Windows Explorer, the workbook will not open.

Is there any specific code I need to include in my
auto_open/auto_close sub's ?

The add-in is loaded and all of the macros are available,
and I can choose File-Open and open any file successfully,
but the same file will not open when double-clicked in the
Windows Explorer.

If I remove the add-in all files open correctly when
doubled-clicked

Any Ideas on what I did wrong in my Add-in ?