Question: inconsistent results in maple 12 and maple 15

sign is different runnning the same script in maple 12 and maple 15 in different machine, just using matrixmultiply and matrix(xxx, shape=hermitian)

assume my window 7 infected by virus, can maple prevent virus change

its accuracy?

or

is there any change between maple 12 and maple 15? 

i feel that i will have to make large effort in order to find reason such as reinstall maple 12.

window 7 maple 15

[[a = 3.720799777 10 , b = -3.720817167 10 ]], 0.3469023622
[(-0.737729376724384 + 0. I) ((-0.737729376724384100 + 0. I) a

+ (-0.738311510115612690 + 0. I) b) + (-0.590656319609631

- 0. I) ((-0.590656319609630831 + 0. I) a

+ (-0.589459378339369122 + 0. I) b) + (0.326925800179577

- 0. I) ((0.326925800179577230 + 0. I) a

+ (0.327770888454982090 + 0. I) b) = -0.736196608749071 + 0. I,

(-0.590656319609631 + 0. I) ((-0.591008582207233624 + 0. I) a

+ (-0.589459378339369010 + 0. I) b) + (0.331003458223746

+ 0. I) ((0.331003458223746439 + 0. I) a

+ (0.327770888454981812 + 0. I) b) + (-0.735625969091165

- 0. I) ((-0.735625969091165288 + 0. I) a

+ (-0.738311510115613134 + 0. I) b) = 0.327869065042947 + 0. I

]

window 8 maple 12

[[a = 0.2249293777, b = 1.221244758]], 0.9888653482, "************"
[(0.737729376724384100 + 0. I) ((0.737729376724384100 + 0. I) a

+ (-0.738311510115612690 + 0. I) b) + (0.590656319609631053 - 0. I)

((0.590656319609631053 + 0. I) a + (-0.589459378339369122 + 0. I) b) +

(0.326925800179576676 - 0. I) ((0.326925800179576676 + 0. I) a

+ (0.327770888454982090 + 0. I) b) = -0.736196608749071002 + 0. I,

(0.590656319609631053 + 0. I) ((0.591008582207233624 + 0. I) a

+ (-0.589459378339369010 + 0. I) b) + (-0.331003458223746605 + 0. I) ((
-0.331003458223746605 + 0. I) a + (0.327770888454981812 + 0. I) b) + (
-0.735625969091165178 - 0. I) ((-0.735625969091165178 + 0. I) a

+ (-0.738311510115613134 + 0. I) b) = 0.327869065042946218 + 0. I]
7