Programs didn’t auto save and regularly crashed. It was extremely common to hear someone talk about losing hours of work. Computers regularly blue screened at random. Device drivers weren’t isolated from the kernel so you could easily buy a dongle or something that single-handedly destabilized your system. Viruses regularly brought the white-collar economy to its knees. Computer games that were just starting to come online and be collaborative didn’t do any validation of what the client sent it (this is true sometimes now, but it was the rule back then).