It's community servers forcing a download of a new radar file, overwriting the stock file. Delete it and verify cache. They are in Csgo/resources/overviews. De_dust2_radar.dds is the one for dust2. It can also happen with the txt file that determines what is displayed when the map is loading. Again, just verify cache/delete the problem file. Setting them to read only will probably prevent them from being overwritten in the future. Probably.