Well, changing the mysql.jar to the same that found in OF 3.8.2 did the trick. No more problems and weird behaviors here!
Mysql 5.5.33 + JDBC 5.0.8 = YES
Mysql 5.5.33 + JDBC 5.1.30 = NO
Bonus: I think the new OF + JRE 1.7 uses less Java Memory.
Thank you, guys! 