This happens often if you are saving the files to a live drive or shared drive. When you save the file you have been working on and it doesn't sync then you get this error. I have gone through SW explorer and have successfully corrected the problem. You can also try and correct the sync problem by going to start button then type offline manager and click it in the tree and selct enable offline files and then restart computer and it should automatically start syncing offline files and then look for errors and then right click on them to try and fix. Hope this helps.