Being particularly skilled in computer maintenance is often a large burden in some ways. Being capable of effectively maintaining a computer is a life skill that can grant you access to virtually limitless amounts of information, numerous employment opportunities, and a vast number of types of entertainment and forms of self-expression. Self-expression can be explored on computers through the ability to design graphics, put together and write personal blogs.
However, the moment friends, neighbors friends, and perfect strangers realize that you've got an unusual amount of computer finesse you will be seen as a useful resource for their toolbox (think hammer, or screwdriver) for their uses. People that don't have a deep understanding of computer use often lack altogether what are known in psychology literature as the "meta-cognitive" abilities to assess their own ability. This, consequently, results in a scenario known as the Dunning-Kruger effect.
The Dunning-Kruger effect is a documented phenomenon where men or women who've the least amount of skill or knowledge on a given subject matter actually believe that they are of a very high skill level, and often even rate themselves even higher than those who actually are in the top tier of skill in a skill or subject.
As an inevitable consequence of the Dunning-Kruger effect, what can result is that men and women will often ask a particularly able computer user to help them "fix something really quick" without knowing the actual depth of a given computer problem. Then, said computer technician, agrees, as a well meaning favor, without knowing what they are actually signing up for and feel obligated to continue working on the task until it is fixed (possibly even hours later).
There's a few solutions to this problem. One is to make it a matter of habit of having an actual script that you deliver to absolutely everyone who requests assistance with a computer. This script should inform the requester that your offer of help doesn't guarantee future support for free, nor any responsibility if things end up even more broken. One should also set a firm limitation to the number of hours you're willing to invest on it, and inform the requesting party what that time limit is before you begin working on it. Depending, of course, on the personal relationship with said person or persons you might also take into consideration establishing an hourly rate you might be willing to charge that's reasonable.