Thank you for your quick answer, sorry for being late to give news.
1. The driver couldn't be installed, no trace found in add/remove software, so not much to do about it.
2. You kindly sent a link, but it is to a firmware; you talked about one to a driver.
The problem also happens when the printer is offline, not connected at all, no network connexion, printer down, switched off.
So a driver seems to me too a better solution as the problem happens at the installation on the computer.
There could be a conflict due to installed softwares: did you hear something about this ?
Have you tried un-installing the printer and re-installing it with the Xerox Driver found HERE?
At the installation of a 6515, I get the error " wtof " in "Msvcrt.dll " (the full message in french is
" Le point d'entrée de procédure _wtof est introuvable dans la bibliothèque de liaison dynamique Msvcrt.dll "
[Entry pint point of procedure _wtof can't be found in the DLL Msvrct.dll]
I tried using the EXE install file (The error message comes directly).
Using the .inf file brings that error message at the end of the installation.
Ms Windows 2000 Pro is clean, checked by SFC /scannow & antivirus.
Thank you for reading this