Both are right, the statements are consistent. The problem is created by a combination of an erroneously limited path length for the shadow map temp files and from a sometimes less than optimal placement of those files. If your installation happens to be in a place with a long path name, it is rare, but not completely unlikely to hit the problem. Or, if your scene file is loaded from a location with a long name, is again possible to hit the problem. Most users stay within the limit, so they'll never see the problem. Some exceed the limit, and their shadow maps are gone.