While attempting to export a raster dataset to the grid format, ArcCatalog crashes.
Most likely you are running out of disk space.
Clean the temporary files and folders that are left over in the location where you were writing to. Do this before restarting ArcGIS, as the lack of available space may cause additional problems.
Before re-attempting the procedure, be sure to make more space available on the target disk, or use a different disk.