Hello,
I tried the first suggestion and then double clicked on the HP Printer icon, and exactly the same problems re-ocurred. Then I tried the second suggestion (manually adding to the Registry) and the result was the same. Then I thought, to be safe, that I should run the backup file for the Registry, which was suggested in both steps. When I tried this, it seemed to run the backup - but I got a Windows error message saying that the whole backup could not be completed! This scares me! My computer still seems to run fine, but now I am worried that in addition to the HP problem, I might also have a screwed up Registry!
Just to reiterate - when I double click on the HP Printer icon nothing happens except that the mouse pointer gets a little circle around it that seems just to quiver and do nothing. Then when I open Task Manager and look under the Processes Tab, numerous instances of HP Printer Assistant are running (so many that I cannot count them) - and more keep getting added as I watch! Then finally after some time my computer just seems to reboot by itself and takes me back to the intial logon screen of Windows. Thanks again; I hope this can be sorted out.