Salix OS

This could be either a problem with the internet connection (most likely) or with your RAM. You can test your RAM with something like memtest.

Are there issues with the network connection with other devices? If you're using wifi, plug an ethernet cable, or the other way around.

Wait a bit (maybe 24 hours) and the atom package will be available from slapt-get. Your mirror hasn't synced yet and the one you're trying to install now is from a slackbuild. But that doesn't mean that you don't have to fix your networking issues.

I’m not convinced this is an Internet issue. My other laptop uses wifi and there’s no problem at all. No problem either with my phone. The other PC doesn’t use wifi so I won’t take it into account. I’ll wait one or two days before trying again, as you’ve suggested. Meanwhile, I’ll pay attention to this laptop’s Internet connection and take a look at memtest. Can’t see why there would be an error on this side, but it won’t be bad to check.
Is the memtest86 package available the good one to use, regarding I’m running a 64-bits distro? The question may sound stupid, but since I’ve never used memtest, I’d rather ask.

Thanks!

To be frank, I've never used the packages. I think memtest should better run without the overhead of any OS. They provide their own ISOs.
http://www.memtest.org/

Let it run overnight.

I checked the memory, and after several hours and 4 passes, no error, everything was OK. That’s good, though I don’t understand why I got the errors Igve encountered earlier, then. Mystery…

Then I installed Atom using the package manager and, apparently, it runs well. Thank you very much!