Scanner approached by another application does not respond

After a long and perfect service my hp scanjet 2200c stopped working. When I click the icon the scanner lamp goes on, a click is heard and that is all. Often a window opens saying that the scanner is being accessed by another application which I am required to exit before continuing. Have no idea how to do this. Very seldom, after an hour or two, the scanner window comes up and the scanner performs a scan.
My HP500 laptop runs on Windows XP. Other than this it works perfectly. I have the scanner installation CD.
Many thanks for your time and help. Sincerely, Ephraim