Adding Applications (sometimes known as helpers) to FF 3.0,6

[#1]

Hi
Here's an interesting one that I'd like to be able to solve purely out of interest  but cant.
After using Foxit I uninstalled it and reinstalled Adobe but it does not seem to have re-registered itself with firefox.
Nppdf32.dll is in the plugons folder but it does not appear in the list of applications, have also tried registering the DLL using regsvr32 but it returns an error that an entry point cannot be found.
PDFs open but not inline in the browser even though the option in reader is ticked to display in browser.
Anyone know how it can be added through the UI, command line or the registry?

[#2]

What happens when you:
Tools | Options | Main | Manage Add-ons | PlugIns    ?
I see Adobe listed with enable or disable button.
Failing that - maybe uninstall FF and reinstall ?

[#3]

Your better without it depending on the version Adobe used to crash FF for me so now it just downloads it. Off the top of my head when you click on the file and its says download it should give you the option to open or download if you say open with FF and all ways do that it should work I think

[#4]

Hi
@Mal It does not appear in the plugins list which is why I was wondering whether the plugin may not have registered with the system corrrectly.
I can open PDF files and it appears if the MIME type is specified in a page it will open.
As I said, just curious really, hence the reason I asked whether anyone knew of a registry fix either (but don't like rooting around in there if I can avoid as it ain't pretty!)
Cheers for the responses