Most likely this is not a jForum bug since the error is occurring on a fairly simple prepared insert statement.
Judging from the error info, it looks like your JDBC driver is not properly translating the date into SQL that your MySQL server understands.
Since you have an old version of Java and MySQL, you may need to find a matching older JDBC driver who's setTimestamp method will set the value to match your's MySQL's expectation of a DateTime field.
FWIW, MySQL is infamous for changing the way it deals with Dates and other "specialty" fields... mostly to move from it's non-standard methods to more standards based. [originally posted on jforum.net by monroe]