I have been playing Ishar for quite awhile but now I run in a very strange problem:

My current party is - Aramir, Kiriela, Obarmon, Zaloran, Morgula. For some reason, all of them except Kiriela have a icon of "ying-yang" in their status (screenshot attached), and if I order anyone to attack something, instead they attack each other - Aramir/Zaloran attack each other, while Morgula/Obarmon do the same.

I know that the game use a system of aligment/psychology where some party member can hate each other, and in fact for some reason after visit a npc which give some advices he warned that Aramir and Zeloran hate each other. But he did not say anything about Obarmon/Morgula. The problem is I have no idea why this happen or what is going on.

The manual say that icons which appear in the physiology boxes show the character condiction, and say to look on "spells symbols" (p.8) problem is, that there isn't such section on the manual. The other problem is that this characters are quite vital to finish the game I can't just get all of them killed and replace them.

Any ideas?

I had the same problem, and this is what it is. They've been hit with a certain curse, and that's what making them attack each other instead of the enemy.
You need to cast a spell to remove the curse, or something like that.

Yes, in fact by looking at the Ishar 3 manual the spell which casted was Inversion, the question is, which spell or potion remove this condiction?

You will need to cast the level 4 Cleric spell inversion on them. They have had it cast on them already which inverts their alignment. You need to change it back.