forrtl: severe (64): input conversion error

Hello!
This may be a simple obstacle but I am clueless to resolve it.
Thank you in advance to help me to fix it.

Below is my section of code, I am getting the  error in line 2 of which I have no idea of its origin.

!-----------------------------------------------------------------------------------
1.   READ(14,*) IFRAME ! !.. Actual # of MC moves
2.   READ(14,*) N_Si      ! !.. Number of Si atoms
3.   READ(14,*) N_O2     ! !.. Number of Bridging oxygens (BO)
4.   READ(14,*) N_Ox     ! !.. Number of Non-reactive OH

!----------------------------------------------------------------------------------------------

Integer is defined in the program previously as

!--------------------------------------------------------------------------
    INTEGER::N_MC, N_Si, N_Ox, O2LABI, N_O2

!---------------------------------------------------------------------------

     File 14 from which I read the data is

!------------------------------------------------------------------------

       508 !.. Actual # of MC moves
      1000 !.. Number of Si atoms
           0 !.. Number of Bridging oxygens (BO)
           0 !.. Number of Non-reactive OH

!-------------------------------------------------------------------------

 I have compiled the code as

 ifort code.f90 -fpe0 -traceback -CB -O0 -o a.out

And running the code using pbs on 64 bit linux based cluster.

The program runs fine and there is also no run time error. However in between suddenly this error is flagged and program is suspended.

Your suggests of any kind is highly valuable.
Thank you