Sharepoint Designer closes connection

I'm trying to connect to my SP2013 site using Sharepoint Designer 2013. I can open and view files (master pages and site layouts) fine. However, when I try to save the files, I get the error: The server unexpectedly closed the connection. This happens to all files.

I went to my Sharepoint logs, and saw this:

01/21/2015 12:05:59.76* w3wp.exe (0x3250)   0x31FC  SharePoint Foundation   DistributedCache    ah24w   Unexpected  ...mmunicate with the server : net.tcp://INFOSTORE:22233 
    at Microsoft.ApplicationServer.Caching.DataCache.ThrowException(ResponseBody respBody, RequestBody reqBody) 
    at Microsoft.ApplicationServer.Caching.DataCacheFactory.GetCacheProperties(RequestBody request, IClientChannel channel) 
    at Microsoft.ApplicationServer.Caching.DataCacheFactory.GetCache(String cacheName) 
    at Microsoft.SharePoint.DistributedCaching.SPDistributedCachePointerWrapper.InitializeDataCacheFactory()'.  0bfae19c-41de-f0f3-2879-3005a100e057    

I couldn't find documentation about Sharepoint Designer using port 22233, and anyway, since I can connect, and view files, I'm not sure what the difference is.