One of my consulting business clients was reporting trouble with one of the machines in her office.
She ran an employment agency for permanent and temporary positions. She employed some people to handle clients and some to schedule the candidates for the temp positions. I took care of her database, her computers and her network.
She had half a dozen Windows 2000 computers on her network along with a Windows server. In those days, Microsoft 365 had not yet been invented and all the workstation computers had Office installed on their hard drives.
The troublesome machine was used by one of the owner’s employees who handled correspondence with her clients and candidates. The machine was “slow”.
The machine’s regular user was off for the day when I went in to check on her computer. I ran the usual virus and update checks. Since Outlook was the primary tool used, I thought that maybe a virus had been downloaded along with a candidate’s resume or a client’s requirements document. When nothing seemed amiss there, I started checking the file system. I was shocked to see that the Outlook .pst file was taking up over a third of the hard drive. (Hard drives were small by today’s standards. The server, for example, had a 120GB RAID array.)
I started looking around in Outlook itself and immediately noticed that there were over 6,000 files in the “Deleted Items” folder, most with attachments. (Yes, a six with three zeroes...) I showed the boss and she shook her head and offered a few expletives. Thinking I was solving the problem and doing the hapless user a favour, I emptied the Deleted Items folder, de-fragmented the hard drive and restarted the machine. It was now back to normal, even downright perky.

The next morning I got an angry call from the woman whose machine I had resuscitated: “What did you do with all my files??!!”
Apparently, not knowing how to download an attachment and save it to the network drive or how to create a new folder in Outlook, she had been “storing” everything in the “Deleted Items” folder of Outlook.
Luckily, I still got paid...