I help maintain a Managed Technical Service, based on a Citrix platform and I have a user with a strange problem.

They claim to have entered data on a spreadsheet, saved and exited, and then upon re-opening later, the data is not there. They then reported an entire worksheet disappearing before their eyes.

Now, I'm pretty sure this is just user error, but they are absolutely adamant that it is not. So, for peace of mind, could anyone please advise me if they have encountered any such problem before, or is my user just useless?