I cant see the result on REPETIER-HOST V1.06

Vertex 3D Printer Vertex - Printer software (repetier, slicer, ...)
1

Hello,
For some days when I slice an object, I cant see the result, but the *.gco seems correct.
What happens with REPETIER-HOST V1.06 ?
Should I re-install it or what?
thanks.
Henrig