0-01-2016 when making a new activity

a few days ago I wanted to add an activity in iCal/Calendar for January 8, 2016

while entering the correct time, etc., I noticed that the date was 0-01-2016

after completing the entry, the activity was stored on the correct day.

in order to solve this, I went to System Preferences...>Language & Region>Region:...and re-set the "Region"

next I also restored the defaults.

than I opened Preferences Folder and moved the com.apple.iCal.plist file to the Desktop.

finally I did to install the combo-update.

after that, I did a complete re-install, without erasing my SSD. again no result.

as I have done a clean install about 2 months ago and that I feel the mistake is so small, that I don't feel much for doing in other clean install.

in the meantime, I found this little problem occurs on each and every 8th of any month

note: this question has been discussed here as well:

0-01-2016 when making a new activity