help with virus and related

[timmyaung]

The other day, my computer got infected with a virus including my external (which has important stuff). When I sent both to the computer technician whom i bought the computer from (now that I hate), I told them very clearly to use my computer (already infected but still usable) to disinfect my external which is very important (un-formattable). Just today I got my computer and they formated my computer and told me to dissinfect my hardrive myself (made both me and my father very angry). They told me that if I add a virus program to my computer, I would be able to at least scan my hardrive without the virus infecting me. I was just wondering if that was true since I don't trust him anymore, and that just a virus program would help.
*Another topic relating this* Earlier this year, when I bought my computer, I installed both Avast(virus program) and Zonealarm(firewall) to protect my computer. During that time, I did not recieve any viruses and my computer was very protected but later, my computer malfunctioned and could not start up. I brought it to that technician and told me that I had to many protection programs. I believed him so I only installed Avast and now I have the virus. Another question I have now is that if I could install both Avast and Zonealarm to protect my computer.
Thanks so much for any help!!!

[Jintan]

Welcome to CTH timmyaung,

Emotions like "hate" change your day, but do little to change another person's day. Done is done, so do something other than hate.

You say you had an infection that also infected the external drive, which suggests an autoload-type infection. If you borrowed an infected flash/thumb drive from another person, it would immediately infect all attached drives on your computer when inserted. And once you computer was infected, it then would immediately infect any other drives inserted. Based on that scenario, a more immediate question would be - what happened to the infection on the external drive? I will say this - if the repair person does not understand this type of infection, and attached your drive to their system...well, I just said what would happen at that time. An antivirus and firewall for security, if kept updated and regular scans done, are just fine for security. See more info here on that.

So, what happened to the external drive, and any thumb/flash drives, inserted into this computer while it was infected?