Bizarre Excel 2007 crashes with Excel add-in

[Joannes Vermorel]

I am encountering some bizarre issues while developing a COM add-in
with Excel 2007.

In a nutshell (once the add-in is installed)
- I start Excel 2007 directly (no file being loaded), everything
works.
- I open any spreadsheet from the already opened Excel instance,
everything works.
- If I start Excel 2007 by opening an Excel 2007 spreadsheet (i.e.
clicking on an XLSX file), add-in crashes.
- If I start Excel 2007 by opening an Excel 2003 spreadsheet (i.e.
clicking on an XLS file), add-in does not crash.

The detail of the problem is further described at
http://sourceforge.net/tracker/index.php?func=detail&aid=1935231&group_id=186223&atid=916416

I am bit lost with this issue. Does anyone has an idea what could
cause such a behavior?

Thanks in advance,
Joannès