Ian LyttleI'm guessing that your `Sys.timezone()` corresponds to Central Europe Time.
For this timezone, on 1997-03-30 the clocks skipped from 02:00:00 to 03:00:00, so 02:43:12 did not exist as a "wall-clock" time.
Perhaps R skipped back an hour to the wall-clock time that did exist?
(just saw other responses that already answered, sorry)