Did you recently prepare a clone and open that on a machine with a different language setting?
No, I understand what your thinking, date format issue, however no I have not.
The date format has always been the same mm/dd/yyyy.
Source file is still using the correct format too.
Really weird how this came on at midnight without any changes.
Are you importing the date directly from teh csv or is it an autoenter calculation? I had a similar issue, it turned out to be that a windows server update had screwed the time/date settings in windows server and the autenter creation dates were all thrown off.
I have had similar issues. The file in question started life as a template developed in England, then had some time being worked on by a developer in the Philippines. So I think the root cause may have had something to do with the original country code of the file.
In my case we were trying to do updates with 360 Works MirrorSync. The solution may not be helpful to you. We used getasnumber( datefield) and GetasDate(numericValue). This resulted in the updated record getting the correct date.