The PARI/GP Thue equations solver gives wrong results when they are conditional on GRH.
Affected are at least versions 2.5.1 (latest) and 2.4.3.
? p=x^3 - 18*x^2 + 81*x + 1;a=3^3
%1 = 27
? t=thue(thueinit(p,0),a);[#t,t] \\ conditional on GRH
%2 = [3, [[0, 3], [3, 0], [19, 2]]]
? t=thue(thueinit(p,1),a);[#t,t] \\ uncoditional
%3 = [4, [[0, 3], [3, 0], [27, 3], [19, 2]]]
Found on the pari-dev mailing list http://permalink.gmane.org/gmane.comp.mathematics.pari.devel/3629.