my favorite bug, is the instant 9999 JP bug...

you go into a job that can scroll such as "Chemist" and click on a item to learn... when it asks Is this okay? YES/NO DONT HIT YES instead press and hold square and then tap either up or down on the directonal pad... try to make the cursor land on a skill that you dont have enough points to learn.. then release square and then select YES....

then it will either gray out all the abilitys and give you 0000JP wich then you have to exit the learn screen and re enter it and you will find you have 9999JP in that title... or it will stay at 0000JP untill you exit and re enter but will allow you to learn all abilitys w/o exiting and re entering...