Firefox is already running, but is not responding.

I made a addon of Firefox. It will clear the error, "Firefox is already running...".

The following matters were suddenly happened on my Firefox.

1. When Firefox is running, I open any html files on Explorer or click any URLs on any other applications (for example, Skype). So, Firefox displays the error, "Firefox is already running...".
2. When Firefox never exist, I open any html files on Explorer. So, Explorer displays the error, "xxxx is not found....", but html file is normaly opened by Firefox.

I tried to find the cause...

1. When Firefox is launching, Firefox tries to create Windows DDE server. But its failed. So, because Windows system can't find the first instance of Firefox, it will try to make the second instance of Firefox.
2. I don't understand the detail. This error is displayed by Explorer(USER32.dll).

I made another account on Windows. These problems were perfectly cleared on new account. But I keep to use current account..
So, I made the addon of Firefox for clearing these problems.

I took these approaches on my addon for clearing errors.

1. When Firefox launches, My addon launches my original Windows application(dde2socket.exe). It creates Windows DDE server. So it communicate with my addon through socket.
2. When dde2socket.exe launches, it tries to find the error message, "xxx is not found...". If there is the message, it throws "WM_CLOSE".

For the time being, I made a success of clearing errors on my environment(Windows XP). So, I release my addon here.
Click the following link by right button of mouse and save as name to your local disk and drag & drop to the Addon Manager Window of Firefox.

NotYetRunning10.xpi

This addon includes a Windows native executable file(dde2socket.exe). If your environment is Vista or Win7, maybe it requires "UAC" authentication at the first time of launching this addon. Dde2socket.exe will be launched at the time of launching Firefox. You can find the icon on your tasktray. Dde2socket.exe will be closed at the time of closing Firefox.