Crazy. I put the "Control" flag on all the guest characters so I could control them, which is pretty fun... until you try to use "ReEquip" on a guest character who is not currently in your party. I guess the game can't decide where to put the item, so it locks up, and then eventually your PSP shuts down.
Reequip works fine on guest characters who ARE currently in your party (on your formation screen).
Long story short: if you have controllable guest characters in your patch, make sure they don't have Reequip equipped... either set ReEquip to 0%, or change all the Support slots on these characters (for example, Algus/Argath starts with "Random" for his support slot in the battle in the Mandalia Plains where you first get him...)
I never had this problem... my controllable guests always brought up my inventory menu. Curiously enough though, their items were not included. The game is very clever, hehe. So it might be best to avoid giving them Re-Equip because odds are they will not be able to get back their own gear.
Just choosing not to re-equip would be a sensible solution lol. But Tzepish, I would be a little pissed at the game if i actually did want to re-equip a guest during a battle, so thanx for the info