When you play Phantasy Star Online in online mode the game saves your starting online mode. At this point if the GameCube turns off for any reason your entire item pack will be removed, except what you were last saved to be equipped with. Your item pack is only saved if you leave online mode by selecting QUIT GAME from the main menu.

Now if there is a disc read error or you loose power to the GameCube, there isn't much that can be done at that point.

In other circumstances the game will get stuck. Such as the lobby/pioneer/area fails to load. Or the menu can't be opened (this happens in the central control area laser maze of the A New Hope and Military Strikes Back quests)

The game hasn't frozen in these cases, the music is still playing, but you can't select the QUIT GAME option either. In these cases do NOT reset the GameCube. Instead disconnect the GameCube from the internet by unplugging the network wire or switching off the router (for GameCube players on the Wii, the later may be your only option).

This forces the game to sense a disconnect and it will immediately save and return you to the main menu. When this happens you have done a save end to online play and your item pack will be saved.

The reset button on the Wii forces a save.

The reset button on the Wii forces a save.

I had made an assumption. I will stand corrected.

I believe that pressing all the face buttons on the GC controller for a soft=reset also forces a save - handy for those Endless Warps and connection issues.