Problem encountering in 2003 Outlook

Hello everyone,
I have surfed the internet but I did not get my answer yet.
I got the person is very well organized. The email he kept in different folder and subfolder. Once, all on a sudden, his some emails found in the “Deleted Item”.
There is no link between them that I can see. The emails are coming not only from one folder but also a lot of other. The 700 Mo and 650 Mo mailboxes suddenly have been transferred to “Deleted Item” strangely.
Does someone know the reason of happening this? To let you know this is without any rule and auto archives in his account. So, please help me to solve this problem.
Thank you in advance for your help.
