hi lenka,
we often face this type of issue if the server gets too busy, or we are promoting a lot of columns say above 150, just a suggestion, try publishing the same form on a different document library, if the form publishes without any errors we definetly have an issue with your publishing to your old document library.
one more thing while publising to your old doc lib, you can check on the property promotion screen, click on any of the promoted properties, see if it maps to some old column or creates a new column, idealy it should be poining to some old column, only the newly promoted fields should create new columns