threats to my computer

Unauthorized Access
This is called hacking
Use anti-virus software and keep it current. Installing an anti-virus program can keep viruses and other nasty programs out of your computer. Trojans allow hackers to take control of your computer and send spam and other harmful programs. Should you get one, a good anti-virus program knows how to quarantine and delete it without letting it cause damage.
Activate a firewall. Many people use software or hardware firewalls to prevent hackers from gaining access to their files through ports or other points of entry. Windows comes with a firewall, which you can find out how to set up by going to the control panel and clicking on "Windows Firewall."
Keep track of system events. Check your system log often to find out what your computer is doing. If you're getting notices about any programs you don't remember starting or installing, then be alert. Watch out for any Warning types and TCP/IP messages.
Make sure your operating system is up to date. Windows updates are crucial to protecting your computer from recently discovered security holes. Updating stops hackers from exploiting these vulnerabilities.
Install patches when they arrive. When hackers discover a new way to enter your computer, its usually through a common program such as Adobe Acrobat. Stop hackers by installing security fixes and patches when they become available, as many of these are developed to fix security issues.

Internet & Email
To prevent this is to not open any attachments in email that you don't no who they are sent from.
3. Viruses, Trojans & Spyware-
Viruses, Trojans & spyware is where you have a unauthorized access to your files.
4. Power Failure -
A power failure is a short- or long-term loss of the electric power to an area.
5. Natural Disaster -
A natural disaster can possibly be lead to a power failure, which could lead to unauthorized access to your files.
6. Data Corruption-
Data corruption refers to errors in computer data that occur during transmission, retrieval, or processing, introducing unintended changes to the original data.
7. Peer to Peer Access.When a group of computers are connected to the same hard drive. eg: Kings College.