[EpiData-list] Lost information

Hi, Recently, we have lost part of information in the data entry file that we've entered earlier, and I'm wondering if someone else have experienced similar problems. Recently, our data entry staff found that information she had entered the other day disappeared from the file, mainly the ID variable two other variables next to it. The strange thing is that not all of the cases lost the information. Only about one-third of cases lost this information. We're investigating how this happened, and before concluding it might be results of human errors, I'd like to check if this kind of accident has happened to someone else. We're using EpiData 2.01 version. Thank you,

Jin