Q: Nothing happened when I launch Extension Manager.

Question

1. Kill Extension Manager by Task Manager( Windows ) or Force Quit( Mac ).
2. Remove files below.
    Windows( EM CS5.5 and earlier ): "C:\Users\<UserName>\AppData\Roaming\Adobe\Extension Manager CS\Configuration\Extensions\exman_uiPreferences.xml"
    Windows( EM CS6 ): "C:\Users\<UserName>\AppData\Roaming\Adobe\Extension Manager CS6\Configuration\exman_uiPreferences.xml"
    Mac: "/Users/<UserName>/Library/Preferences/Adobe/Extension Manager CS/exman_uiPreferences.xml"
3. Launch Extension Manager again as administrator.
4. If steps above still do not work, you can check if you have some flex-based software installed on your machine. Some of them conflict with Extension Manager, such as Flash FireBug. Uninstall them or delete all files in the folders below after backup.
    Windows: "C:\Users\<UserName>\AppData\Roaming\Macromedia\Flash Player\#Security\FlashPlayerTrust"
    Mac: "/Users/<UserName>/Library/Preferences/Macromedia/Flash Player/#Security/FlashPlayerTrust"
     "/Library/Application Support/Macromedia/FlashPlayerTrust"

Answer 1

I also have this (on Windows XP Pro 64), happened after I installed the latest Avast a/v last weekend after renewing my subscription, but, it may not be the cause. I uninstalled FF, removed all registry enrties and re-installed FF.
But, same as before, I click FF to launch, I see it appear in Task Manager Processes, it does not appear in the Application list, and I can get up to 3 or 4 instances of FF in Task Manager Processes. I end each process to get back to one, or none. Sometimes removing one will remove all, so, there is something causing an interdependency between the multiple FF processes.
Before this happened, about 2 weeks ago, FF somehow made itself primary browser (I run Chrome, IE, Opera & Safari for checking web build work). I put it back IE as primary browser, but after that, whenever I opened any email link in Outlook, IE would appear as a blank page and FF would also open with my default home webpage. If I click the Outlook email link again, the link target would then open in IE leaving FF still showing my home page. Weird.
I have re-set the URL:Hypertext Transfer Protocol ( and the similar ones) using Folder Options / Advanced / Edit Open to set it back to IE for application to be used, and tried disabling 'Use DDE'. Something keeps re-generating it back. Given up, just click the email links twice.
Does any one have an answer to FF not loading, its my essential main browser for much of my work.
Regds Jonathan