One morning Wilma, the print shop manager at a beer distributor, discovers that her computer has a virus. It’s no big deal — sometimes bad things happen to good computers — so she cleans up the system and gets on with her day.

But a few days later the system is infected again.

Considerably more annoyed this time, she contacts Betty (the company’s sole IT person) to get some assistance and make sure the system is 100% clean. After disinfecting the system, Betty checks the browser history and finds that someone has been making late-night visits to X-rated websites.

The question then becomes, Who is using company resources to watch porn? At most companies, suspicion would immediately fall on the nighttime cleaning crew. But the print shop is located in the warehouse, to which the cleaning crew doesn’t have access.

More likely suspects are the company’s salesmen, who all have access to the print shop, and who often run special events at local bars that can go quite late. The salesmen have been known to show up at the warehouse to return promotional materials and unused stock at all hours of the night.

Betty’s investigation is aided by the fact that the print shop door has an electronic lock that timestamps every keycard event. She checks the log to see who was there when the websites were visited. The log shows — nobody! There is no record of anyone’s keycard being used on any of the nights when the websites were visited. Betty now has a locked-room mystery on her hands.

And it’s solved a couple of weeks later. One of the salesmen is bringing back supplies after a late event and notices several night-shift warehouse workers spending their break gathered around the computers in the print shop. He doesn’t know about the virus infections that Wilma and Betty have been fighting almost every day, but he does know that something isn’t right. The print shop door is propped open, so he strolls in to see what’s going on. Not realizing they have just been busted, the night-shift workers gleefully fill him in.

Most of the materials produced by the print shop need to be picked up by the delivery drivers early in the morning, long before the start of the normal business day. Since the drivers are already on the road by the time the print shop crew arrives, pass-through cubbyholes have been built into one wall of the print shop. The print shop crew loads the cubbyholes during the day, and the drivers pick up the materials the next morning on their way out to the trucks. But these are capacious cubbyholes, big enough to handle a roll of a dozen 20-foot banners — and big enough for a skinny guy to crawl through.

Once inside the print shop, said skinny guy opens the door for everyone else. And since the electronic lock is programmed to lock people out of the print shop, not to lock them in, nothing is recorded in the log.

Sharky has a cubbyhole for your true tales of IT life. Send them to me at sharky@computerworld.com. You can also subscribe to the Daily Shark Newsletter.