Sorry, if I am not expressing myself well enough in English. At the time, when I wrote my last post, I had been unaware, that there even was a TWAIN option for the F4580. I thought it was either WIA or STI. Therefore I had been wondering, if something in the hardware or firmware in the printer would not work, unless there is WIA.
I know by now, that the only place to solve the problem is editing the registry. I have already installed too many different drivers getting it all messed and mixed up.
I found two HP-TWAIN CSLIDs in the registry.
HPcue.twain uses ole.dll and is connected with hpqscnvw.exe from Digital Imaging. This is a scanning access window (hp-scanning), which I can start manually.
HPQ.twain.1 is connected with TwainCtrl.dll, also from Digital Imaging.
Then there is this [HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Twain]
"Standardquelle"="H:\WINNT\Twain_32\hposrc10.ds"
The error message, that the scanner cannot be accessed has hposrc10 in the title. As long as hposrc10.ds is there, I am offered the all-in-one scanner as a choice in the applications, which does not work. When I change the name, it disappears. And I have no idea, where it came from. It is obviously important, but it is the wrong one.
I need to replace this .ds file with one which works. But there are no .ds files not in Digital Imaging nor in the F4580.
So I am stuck again.