virtualbox.org

I created a new machine named DOS 5
I mounted floppy A:

I have all my original disk for DOS 5
I can access A: from the host XP Pro and read files on it

When I start the Dos virtual machine it tries to read A: (I hear the drive's click) then nothing happens.
the windows is black and the cursor does not blink
This means that I cannot finish the DOS installation

any idea?

thank you

Check the "Other Guests" forum. There are guides there for getting DOS guests installed and working. Or you could simply google for a ready-made FreeDOS VM.