what does the "INF" in the covariance matrix mean? an error or not?

the result of my program consists of the following part:

ML covariance matrix
Parameters Estimates Std. err. Est./s.e. Prob. Gradient
---------------------------------------------------------------------
params[1,1] 3.0373 0.0000 +INF 0.0000 2.3687
params[2,1] 1.2092 0.0000 +INF 0.0000 2.4773
params[3,1] 6.1907 0.0964 64.206 0.0000 0.0180
params[4,1] 0.0000 . . 0.0000 -1721.7180

Correlation matrix of the parameters
-INF -INF +INF .
-INF -INF +INF .
+INF +INF 1 .
. . . .

but i dont understand the meaning of the "INF" and dot, does anyone know the meaning?