i have same problem... adding file is ok. but working on files in sync is trouble. i work on some files(xls) in sync, save them, double check every time it seems normal for a while. after a couple time it turns back to first state that i share. all of my work was gone. PCs that we use win7 and Win8, BTsync version 1.2.91. ps: English is not my native lang, sorry for mistakes.