I have a suspicion that someone tried to access my computer over the internet. Is there any way in which I can protect my PC from further intrusion?

Making sure that any remote access programmes that you're running on your PC is password-protected is the most important thing you can do.

After this, I suggest you install a personal firewall program on your PC as well, which will put your mind at ease about any further intrusions.

For those of you not familiar with a firewall — a firewall, according to Wikipedia, is "an information technology (IT) security device which is configured to permit, deny or proxy data connections set and configured by the organization's security policy. Firewalls can either be hardware and/or software based. A firewall's basic task is to control traffic between computer networks with different zones of trust. Typical examples are the Internet which is a zone with no trust and an internal network which is (and should be) a zone with high trust."

It's completely understandable if you don't have a clue what that means.

Let me try to state it simpler: in the case of a single computer, a firewall controls the traffic between that computer and the internet and will only allow the traffic that the user specifies, to access and leave the computer. It's like having a wall around your computer with a door in it, through which the traffic is strictly regulated. Unless you specified that the traffic can enter and leave through that door, it will be blocked.

There are a number of free personal firewalls available on the internet, least of which is CheckPoint's ZoneAlarm for home use. After installing it, it will take some serious initial setup to configure what traffic ZoneAlarm should allow and what not to allow, but after that it will run in the background and do its thing.

Do you know of better free personal firewall software? Then please share it with us by leaving a comment.