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Hi, I am obtaining the following error

Singular crashed -- automatically restarting.
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "_sage_input_13.py", line 10, in <module>
    exec compile(u'open("___code___.py","w").write("# -*- coding: utf-8 -*-\\n" + _support_.preparse_worksheet_cell(base64.b64decode("SS5ncm9lYm5lcl9iYXNpcygp"),globals())+"\\n"); execfile(os.path.abspath("___code___.py"))
  File "", line 1, in <module>

  File "/private/var/folders/n0/xtxhjph92sx243qp7jk1fjkc0000gn/T/tmprpswoC/___code___.py", line 2, in <module>
    exec compile(u'I.groebner_basis()
  File "", line 1, in <module>

  File "sage/misc/cachefunc.pyx", line 1889, in sage.misc.cachefunc.CachedMethodCaller.__call__ (build/cythonized/sage/misc/cachefunc.c:11355)
  File "sage/misc/cachefunc.pyx", line 2545, in sage.misc.cachefunc.CachedMethod._instance_call (build/cythonized/sage/misc/cachefunc.c:14801)
  File "/Applications/sage/local/lib/python2.7/site-packages/sage/rings/polynomial/multi_polynomial_ideal.py", line 3640, in groebner_basis
    gb = self._groebner_basis_singular("groebner", deg_bound=deg_bound, mult_bound=mult_bound, *args, **kwds)
  File "/Applications/sage/local/lib/python2.7/site-packages/sage/interfaces/singular.py", line 2575, in wrapper
    return func(*args, **kwds)
  File "/Applications/sage/local/lib/python2.7/site-packages/sage/interfaces/singular.py", line 2530, in __exit__
    self.singular.option("set",self.o)
  File "/Applications/sage/local/lib/python2.7/site-packages/sage/interfaces/singular.py", line 1162, in option
    self.eval("option(set,%s)"%val.name())
  File "/Applications/sage/local/lib/python2.7/site-packages/sage/interfaces/singular.py", line 590, in eval
    raise SingularError('Singular error:\n%s'%s)
sage.interfaces.singular.SingularError: Singular error:
   ? unknown option `set`
   ? unknown option `sage61`
   ? error occurred in or before STDIN line 11: `option(set,sage61);`

When trying to execute the following code in sage (actually it is the bare minimum needed to obtain such an error)

CF.<a1, b1, b2, q1, q2, r1, r2, d1, d2> = QQ[];
FF = Frac(CF);
R1.<x1, x2, x3, w1> = PolynomialRing(FF,4,order='degrevlex');
I = R1*ideal(b1^2*r1^2*r2^2*x1^2 + 2*b2^2*r1^3*r2*x1*x2 + (-b1^2*r1*r2^2*d1)*x2^2 +
(-2*a1*r1^3*r2^2)*x1 - q1*r1^3*r2^2,(-b2^2*r1^2*r2*d2)*x1^2 + 2*b1^2*r1*r2^3*x1*x2 + b2^2*r1^2*r2^2*x2^2+(-2*a1*r1^2*r2^3)*x2 - q2*r1^2*r2^3,(-2*b1^2*r1*r2^2)*x1*x3*w1^2+(-2*b2^2*r1^2*r2)*x2*x3*w1^2+2*a1*r1^2*r2^2*x3*w1^2+r1^2*r2^2*w1^2-r1^2*r2^2);
B = I.groebner_basis();

Does anyone have an idea of why does this error occur? Any help is appreciated.