Reference: Xara Web Designer Premium 16.3.0.57723  DL x64 Oct 25 2019

Running on: Lenovo 730-15IKB, Windows 10 with all current updates.

When the referenced app is left running and idle for a while, an automatic save is performed. This sometimes corrupts the saved file and a fatal error is encountered. From there the app can only be exited. The saved file cannot be loaded. To recover you have to revert the most recently saved backup copy of the .web file, which may not include your most recent work. This has been happening for at least the past year.