"Trouble writing schematic" message box

Not sure if this is related to Win10 restrictions - I have a new install of LtSpice and I can't save any new schematic.  I get a "Trouble writing schematic' pop up, and then an "Encountered an improper argument.' error message box.  No apparent related faq's or Q&A threads or google related info that I can find as to what may be stopping the save process.  Any thoughts?