* Someone's MacBook doesn't connect to the internet. This is because 1) the wi-fi is turned off and 2) the school has a burdensome proxy policy. On (1), there is a huge disconnect between understanding that wi-fi functions like a radio with an on/off state and how many devices today are persistently connected via wi-fi or 3g/4g cell networks (tablets, phones). On (2), the proxy policy deliberately conflicts with how people expect to connect to and use the internet and entering proxy details is not a common activity for most people.
* Someone has embedded a YouTube video into a powerpoint presentation. The user has saved this ppt on a flash drive and is confused as to why the video will not load. There is already a disconnect between the fact the video is embedded while the ppt file itself is portable. This is a failing of the design of PowerPoint, presentations are very often to be considered portable once saved even though the content in the presentation may not be portable. Further, the proxy blocks YouTube streaming (why god why) so this user would be unlikely to find an app/add-on to rip the video and then pack it into the PowerPoint because this is entirely contrary to how you expect to use YouTube.
* A user's laptop is running very slowly due to virus infection. The user didn't get anti-virus automatically included on their machine even though they are downloading tons of content. This is a massive design fail, anti-virus should be automatic and transparent on new installs.
* A user complains of a computer not turning on, but it turns out the machine is on and the monitor is off. There is a reason why Mac desktops are designed as single machine/monitor units, the disconnect between machine and display is not intuitive or well understood, esp. in the age of tablets and phones that are single cohesive computers with displays. Just try and watch the average person set up a TV set to various peripherals and you'll see this same thing happen.
* A user cannot connect to the internet even after trying various software settings. It turns out the hardware wireless toggle is off. Either the hardware or OS itself didn't inform the user of what was going on, this is a massive design fail.
* A user attempts to log in to a network site/computer. The user dismisses error dialogs instantly. The problem is the machine is not connected to the network via ethernet. This is already a nexus of various design problems: dialog fatigue, the concept of network login vs. local login, and assumptions about connectivity being automatic through wi-fi vs. cabled network connections. The vast majority of people, including programmers, make huge mistakes about this kind of thing all the time, do we expect the average person to get it?
* A user has a new iPhone and is sad about loss of contacts. When plugging in to the user's laptop, the iTunes backup is able to be restored to the phone. iTunes does make the backup process transparent, but terrestrial backups are not nearly as good as cloud backups for this kind of thing. Android makes this much easier for the average person, restores are opt-in by default when setting up new devices and there's not need to physically connect to a computer.
* A user complains of not having internet access. They have associated the browser shortcut icon with internet. As more items were saved to the desktop, the icon shifted from its original location. Mechanics of file systems and browsing file systems isn't well understood by the average user. This is why whole volume backups are the easiest kind of backups to get someone to performs (esp. if those backups are automatic). This is also why Android and iOS devices try to hide the underlying file system, it is confusing and not well understood (apparently even by devs judging by the assumptions on file systems on StackOverflow).
* A user thinks they have a virus. What they are actually looking at is a spam ad designed to mimic native UI of an older Windows platform. There is a reason why scammy malware ads and sites do this, it is effective because users do not conceptually understand the difference between the browser and websites as separate entities from the OS they use the browser on. In fact, most people don't even conceptually understand how browsers and webpages work at all.