I have had this same issue with at least 6 client files.  We have lost the data and had to recreate it because the problem usually occurs immediately after working in the client file so there is no time to backup the file.  Please figure out a fix to this or we will have to quit using the program that we have used for the last 15 years with no problems.  I have wasted at least 8 hours on this problem - PLEASE HELP!