Outlook 2003 is emptying deleted items without being asked

This is def a client side issue as not happening on other machines: when I close Outlook 2003, it syncs with the offline folder and seems to remove all items from the ‘Deleted Items’ folder, even though I did not request this. Can anyone tell me what is causing this? I have tried re-creating the offline folder, but even with a fresh file, this is still happening…