Check your hatch grid setting in <Tools><Options>(Grids and Snap - Grids tab). It looks like you have it set to about 40-50 mils.
From the help page:
Tip:Copper, copper pour, and plane areas are filled with lines on the hatch grid. When the Drafting option Default width matches the Copper hatch grid, the result is a solid. When the default width less than the grid value, the result is a hatch pattern.