Re: XML dates - the dates of the 6 files span the past 2 yrs… what is the significance?

Just to see what is going on.
The npp settings are stored in these xml files.
Depending on the creation/modification timestamps of the files we could determine
if there is a general deletion of those files or if specific files are affected only.

E.g. I would assume that CCLeaner would treat all files the same and delete those after
some time. Now we should see that the modification timestamp, for the files which get modified,
and the last accessed timestamp of the other xmls is more or less the same once you started npp and do your reconfiguration.

In addition it could have been a trigger to remember if you specified some special rules,
for CCLeaner or any other tool, which might have resulted in this behavior.

Cheers
Claudia

could it have something to do with running out of hard drive space? or memory/swap/page?

Only if every restart of npp would lead to do a reconfiguration but if it is from time to time …

Your setup shows that your configuration is saved under the %APPDATA%\notepad++ directory,
could it be that you use some cleaning tools like CCleaner which removes the notepad++
directory or its content every X weeks?
Could you double check the current timestamp of the xml files in the %APPDATA%\notepad++ directory?

Cheers
Claudia

DEBUG PASTE:
Notepad++ v7.3.1 (32-bit)
Build time : Jan 17 2017 - 00:21:10
Path : C:\Program Files (x86)\Notepad++\notepad++.exe
Admin mode : ON
Local Conf mode : OFF
OS : Windows 7
Plugins : autosave2.dll combine.dll ComparePlugin.dll NppColumnSort.dll NppTextFX.dll PluginManager.dll mimeTools.dll NppConverter.dll NppExport.dll

sounds really strange, may I ask you how exactly your setup looks like?
Can you provide the debug-info? (availbale under ? menu)
How do you use npp - I mean do you start it - keep running until you reboot win7?

Cheers
Claudia