CINEB calculate with ISPIN=1 or 2?

[lihui]

Dear all,
I have calculated the reactant and product, the ground state is ISPIN=2. When i continue to search the transition sate, the ISPIN should be set 2? why ?
I have calculated it for four days, it does not finish. The relaxed atoms are 40,only one Fe atom and others are C and O atoms.The follow is my INCAR. If i kill the job,and continue calculating it with other method IOPT=3. The last result is right?
ISTART = 0
ICHARG = 2
IBRION = 1
POTIM = 0.3
ICHAIN = 0
IMAGES = 4
SPRING = -5
LCLIMB = .TRUE.
NSW = 500
GGA = PE
ISPIN = 2
PREC = Medium
ENCUT = 450
NELM = 100
NELMIN = 2
EDIFF = 1.0e-4
EDIFFG = -0.05
ISMEAR = 0
SIGMA = 0.02
LWAVE = .FALSE.
LCHARG = .FALSE.
IALGO = 48
LORBIT = 11
LREAL = Auto
LVDW = .TRUE.

[graeme]

If the system prefers to be open-shell, you should set ISPIN=2 for all calculations.