Better to restrict their access to your PC. I run into this quite
frequently. I've got a standard speech that "Offspring" get on
how to keep their own PC safe. It's one thing for them to get
Malware & all the other "Baddies", but then to let them do it
to your system isn't a good idea.
I would setup your system with only your profile and use a
"Strong" password 8+Characters, Up/Lowcase & some type
of punctuation character. Then set your Screensaver to a
Password protected or a password on Resume if you allow
the PC to hibernate or Standby.
As to their PC, hire a local technician to clean it & then make
an Image for them. You cannot stop them from downloads &
P2P, so fairly quickly it will become congested with Malware.
At least with an Image they can restore it back to a clean state
and start the whole process over again.
Hopefully, someone in your area can not only clean the PC,
but apply software (AdAware, Spybot...) to help keep it clean.
Usually a charge like this will run around $100, a fair price to
keep them off your PC.
Pardon the lecture - but family shared PC's with children (any
age) users will get infested and soon suffer pretty severe issues
with performance.
