hi again, since Angus' post which told me about the debug option I start Lyx with this option from the prompt.
Autosave function is ok and produces a #file.lyx#. But the debug shows the message. "LYX was not able to make a backup copy, beware!". The directory that I indicated in the path in the preferences is U:/lyx/backup and this directory is still empty. (yes, it's on a network) greetings Jay
