After running CCleaner, it seems that Winword's normal.dot is reset to a basic version (the options I had chosen vanish).
With Office ticked in the Applications tab that will happen every time - it's a registry setting that's removed! In order to keep your Microsoft Word settings you must untick Office. The reason that happens is the MRU List of opened files is stored inside the Office settings.
The same is happening exactly to me from the last few weeks. Fortunately, I had a backup of normal.dot file. It NEVER happened before. I think it must be some bug of the last CCleaner version.
Please try to fix it on the next versions.
Thanks!
If it's actually deleting normal.dot in the meantime you can input that file as an exclusion in:
'Options->Exclude' then click 'Add File' and browse to the normal.dot location.
Note: If it's a hidden file you'll need to enable the view of Hidden Files and Folders to select it, or you could just exclude the whole folder it resides in.