Since "23-12-1973 08:49:25
" equates to a unix time of 125484565, which if you add 1 becomes a date of 6th October 2009 04:14 PM (UTC), a couple days before his post, it would seem to me that he has set up his table with a length/limit of 9 on his timestamp field, which is 1 too short. If you store a too long value the MySQL versions I have worked with at least cut them off.
So Zodehala what you need to do is edit your MySQL table, and enter 10 into the Length/Values
input box, then save. You old data will still have the old 9 length data until you fix that with the weapon of your choice (a short PHP script could handle it), but new data will be saved correctly.
Here's a good unix time site with which to figure out stuff like this by the way: unixtime.info
. It's pretty liberal about accepting various date formats and such in the converter, and has a bunch of other features.