What do I do after beaing the mines boss?
After defeating the mines boss, you must go back through the first levels and touch each of the pillars. They are on levels: Forest 2, Cave 2 and Mine 2. After touching them, you must defeat the mines boss again. Only then can you go through the door into the next area.
If I stop playing, will I have to go back and touch the pillars again?
No, if you quit, PSO will remember which ones you have touched.
As seen here:
http://tomeeboy.com/pso/faq.php?myfa...ories=Gameplay