Undefined value found error.

Hai ,
Can anyone help me to resolve this error while solving solid structural mechanics problem,
What is NaN/Inf ?
Error Message :

Undefined value found.

- Detail: Undefined value found in the equation residual vector.

There are 2032 degrees of freedom giving NaN/Inf in the vector for the variable mod1.u.

at coordinates: (-0.000868043,0.0470507,0.120069), (-0.00258011,0.0479841,0.120069), (-0.000868043,0.0493914,0.120069), (-0.00313503,0.0493914,0.120069), (-0.00189941,0.0465659,0.118934), ...

There are 2032 degrees of freedom giving NaN/Inf in the vector for the variable mod1.v.

at coordinates: (-0.000868043,0.0470507,0.120069), (-0.00258011,0.0479841,0.120069), (-0.000868043,0.0493914,0.120069), (-0.00313503,0.0493914,0.120069), (-0.00189941,0.0465659,0.118934), ...

There are 2032 degrees of freedom giving NaN/Inf in the vector for the variable mod1.w.

at coordinates: (-0.000868043,0.0470507,0.120069), (-0.00258011,0.0479841,0.120069), (-0.000868043,0.0493914,0.120069), (-0.00313503,0.0493914,0.120069), (-0.00189941,0.0465659,0.118934), ...