World Not in GZip Format - PLEASE HELP

Hello,
I have been running a server for a while now, and I host it on my computer. Recently, whenever I shut down the server by using /stop, and whenever I re-open the world, I look in the console, and it says "World not in GZip format" or something like that. Anyways, when I log back on the server, I find that the chunks where the last players where before the server stopped, are all messed up. The chunks are in the wrong places, and it causes a lot of damage and very frustrating. It's happened about 3 times now, all with the same issue. I did some research and found that it's when the server shuts off when the world is saving. Now I don't know what I'm doing wrong, I'm closing my server with /stop. Anyways, after I read that, I used /kickall, then /stop, because I figured that the chunks would be un-loaded when the server shut down, so no chunks can be improperly saved. The same error happened. To my surprise, my computer suddenly crashed for an unrelated reason, and the whole server just went with it. When I booted up the server after my computer crashed, to my surprise, the world is 100% fine (excluding the previous chunk errors from when this error happened another time). How can this be? I close the server the right way, and this error occurs. But when it suddenly closes In a crash, it gets messed up. Anyways, now I'm scared to close my server, for fear of the same issue. Please help.