The ornamental design for a columnprotector, as shown and described.
FIG. 1.1 is a perspective view of a column protector;
FIG. 1.2 is an exploded perspective view thereof;
FIG. 1.3 is another perspective view thereof.
The broken lines shown in Figures 1.1-1.3 illustrate environment and form no part of the claimed design. The broken lines shown on the column protector in Figures 1.1-1.3 illustrate portions of the column protector that form no part of the claimed design.