Plugin in windows just doesn't load

Has anyone else ever experienced this problem when developing an NPAPI
plugin on windows?

I have a plugin that doesn't load when the object tag is in the DOM.
It works fine on Chrome and Safari, and it shows up in about:plugins
with all the metadata correct.  There are no errors displayed, and if
I have a debugger attached to the browser it never shows the symbols
for my DLL being loaded.

I've had this happen a few times before, but I have not yet come up
with any even semi-reliable way of debugging it.

Anyone have any experience with this?

Thanks,

Richard