My laptop keeps shutting off at random, what is it?

My computer is fairly new, and I try to keep it cool by letting the fan remain unblocked, though I don't know if the fan is dist-free, and I don't know how to check that. I've run it through plenty of anti-virus scans, all coming up with a "no viruses detected" but it will still randomly shut off at times. My power supply is always full or almost full and it usually only shuts off while it's charging. Is it possible I'm over-charging, and this is the cause? After its random shut-offs, I just wait a few minutes and restart it, and it generally works just fine afterward. I'm not sure whether or not it's a huge problem, but I'd like to avoid a random shut-off at a time where my work is not yet saved, like if I'm writing or editing a photo. I'd appreciate the advice if you have any, thank you!