"Installing COM component" window on bootup -- help?

Every few times I boot or restart, I get a small pop-up window near
the end of the bootup with the heading "Installing COM Component". In the
box is "activex.microsoft.com", and a progress bar, which never starts. The
window just sits there; if I close it, I get the warning "Canceling will
likely result in failure of the current operation."

I have no idea what this is, why it's sporadically appearing, or what to do
with it. It's been going on quite a while, and I can't pinpoint its starting
to any changes on my system, or any added hardware.

Can anyone help?

Thanks very much.