My computer recently crashed, so I rebuilt it and installed office
2003, VS 2005, PIA for 2003 etc (as it was before). But very
strangely, all my C# based Excel automation add-in stopped working.
In fact I can load them into Excel without any error message, i.e.
Tools / Add-In / Automation / Selec the class, click OK. However as
soon as I close the add-in dialog box and reopen it, all the ticks are
gone. There is no error message in the whole process.

I have tried to recompiled the code etc, without any luck. There is
no error in the event log as well.

I don't think it's related to the code, but more or less related to
some configuration. Can anybody have any hint for me?

Also, is there anyway to turn on Excel logging so I can see what's
going on? (I suspect there is an exception being thrown silently
during the loading / activiating the add-in, but I could not intercept
it by lauching VS debug session.

Thanks.