Importing and convering dates

Hello,

I need to import a text field of dates (format like: Sep 4 2009) from a CSV file into a date of the user profile. The import process functions since it is written in the DB table, but it is unable to read it. Looking at the database, the date field that is supposed to receive the data contains information in the format:
a:3:{s:5:"month";s:1:"2";s:3:"day";s:1:"8";s:4:"year";s:4:"1969";}

Any hint?

Thank.