WPX9 crashes

Leaving the notebook for only a few minutes (or just not typing), the standard WIN10 screensaver  appears (standard setting: 1 minute).  After unlocking the computer, getting back to WP is often impossible, because WP ›freezes‹, i. e. crashes.  Only one file open, no matter if recently saved or not.  This happens with imported .docx files (saved as .wpd).  I cannot figure out any reason.  Besides, WPX8 and WPX7 show the same behaviour, older versions (WPX5, WPX3) seemingly not.  Other programs do not crash.  – Any suggestions?