Weird Backup..

[xinete]

Hello,
I have a site that my client is updating the products and they have already around 500, sometimes they claim something is happening the next day after they add some products, like the next day the products are not there, they have been making a backup after they update, so if the next day the products are not there, they just restore the backup file of the day before, just the restore file comes out with a couple of glitches, like 1 or 2 images missing or something like that,

Any suggestion, for this?, could be my server that is having problems? or something in the code?

Thanks for your help