Catastrophic compiler error

The following code gives a catastrophic compiler error:

      CHARACTER(*) FUNCTION fmt(rr)
      IMPLICIT NONE
      REAL*8 :: rr
      CHARACTER(LEN=LEN(fmt)) :: cc
      WRITE(cc,'(4g13.5)') rr
      IF(cc == '      0.00000') cc = '  0.00000'
      fmt = cc
      RETURN
      END

D:\Devl.OLI\OLIEngines\src\asap>ifort a.for
Intel(R) Visual Fortran Compiler Professional for applications running on IA-32, Version 11.1    Build 20100414 Package ID: w_cprof_
p_11.1.065
Copyright (C) 1985-2010 Intel Corporation.  All rights reserved.

a.for(4): catastrophic error: **Internal compiler error: internal abort** Please report this error along with the circumstances in w
hich it occurred in a Software Problem Report.  Note: File and line given may not be explicit cause of this error.
      CHARACTER(LEN=LEN(fmt)) :: cc
--------------------^
compilation aborted for a.for (code 3)