The ABCs of cleaning up your PC

The purpose of this article isn’t to go into technical detail, but to offer some basic tools and a sense of how to approach cleaning up your computer. To do that, I’ll make a few basic distinctions and clarifications.

Malicious programs

In reality, “viruses” are one particular class within a wide variety of malicious programs. These are usually classified by their behaviour, their goals and the way they try to achieve them. However, to keep things simple and avoid adding more terms, we’ll refer to all these programs as “viruses”.

We need to distinguish between viruses that do their job without clashing with the operating system or other applications, and those that interfere with the normal running of the computer, making their presence more obvious. There are also others that stay “dormant” until they’re “called” to carry out their purpose. This last class is invisible to the user, and system performance isn’t affected. Broadly speaking, we can come across three scenarios:

1 – The virus runs on our system without causing conflicts, subtly affecting the computer’s performance.
2 – The virus runs on the system and interferes with the normal operation of other programs, seriously hurting the system’s efficiency and/or making the computer harder to use.
3 – The virus is “dormant”, waiting for the signal to run, without affecting the computer’s normal operation.

How can we recognise these situations?

NOTE: Below is a list of “symptoms” that may also be linked to other problems; still, they’re reason enough to start looking for infections.

In case 1, we may notice one or more of the following symptoms:

* The internet connection has unusually low bandwidth.
* Tasks on the computer run more slowly than normal.
* The computer takes much longer to “shut down”.
* At times, the PC “freezes” for a few moments and then carries on as normal.
* The disk is constantly working, even when no programs are running.

In case 2, in addition to the above, we may see:

* Constant error messages
* Error screens, after which the computer restarts (these are called BSODs)
* When you try to run certain programs, nothing happens.
* When you try to browse the websites of certain antivirus programs, they don’t load or you’re redirected to other websites.

In case 3, we won’t be able to spot any symptoms on our computer at first glance.

What can we do if we find some of these symptoms on our computer and want to start a clean-up because of possible threats?

1.- Uninstall any program we didn’t install ourselves
(It’s a good idea to check that they have recent installation dates and to google each program’s name, so we don’t make the mistake of uninstalling an important part of some other system we need)

2.- Uninstall or remove any application that claims to be an antivirus, ONLY IF IT’S DIFFERENT from the antivirus we normally have installed.

3.- Check that our antivirus is up to date and run a full system scan.

4.- Uninstall all browser add-ons and toolbars

5.- Download and run Malwarebytes (http://es.malwarebytes.org/) in full mode. When the scan finishes, select “show results” and then select all the detected items to remove them.

FOR ADVANCED USERS:

6.- Press the Windows key + “R”, then type “msconfig” and press “Enter”.

** Check the following in the “Startup” tab

– That there are no applications with strange names, such as “trsdffs.exe”.
– That there are no applications similar to “cursos.exe” or other variants
– Look up each application in the list on Google to determine whether it’s a malicious program

In any of these cases, as well as unticking the applications, it’s a good idea to look up the removal procedure for each specific application.

7.- If you still have problems, it’s recommended to run Malwarebytes in Safe Mode.

** Restart the computer and, as it starts up again, press F8 repeatedly until you reach a menu

– Select “Safe Mode”
– Then run a full scan in Malwarebytes again.

These are the most basic things to keep in mind when cleaning up a computer. Other procedures require deeper knowledge of how operating systems and applications are structured and work.