Use the following guide to determine your security risk and the action you need to take. Select the options which most closely fit your situation and then consult the table.

My computer

I have a working anti-virus program with the most recent anti-virus definitions and a correctly configured firewall. I have at least one anti-spyware program. My operating system is fully up to date. A

I have an anti-virus program and firewall. I am not sure if they are updated/configured correctly. I am not sure if my operating system is up to date. I have not used any anti-spyware programs. B

I have an anti-virus program but it came with my computer and I have not renewed the subscriptions so it might not be working. I don't know if I have a firewall. I don't know if my operating system is up to date. I don't have any anti-spyware programs. C

I don't have an anti-virus program or firewall. I don't know if my operating system is up to date. I don't have any anti-spyware programs. D

How I use it

I use my computer for business or work.
I have valuable or confidential information on my computer. 1

I use my computer for credit card shopping or internet banking. 2

I use my computer for casual web surfing and playing games. 3

Risk of security, privacy and performance issues

	A	B	C	D
1	Low	Medium	Medium	High
2	Low	Medium	Medium	High
3	Low	Low	Medium*	Medium*

*The risk here is mainly to performance, i.e. the computer will not be functioning correctly.

This table is not meant to be exact, just to show that there can be different approaches to cleaning a computer according to the user: for a user with no security concerns, a major malware infection may be a minor concern; for another user, a single malware item may be a major one. For most users, the question as to whether to clean or rebuild involves weighing up the potential security risks of cleaning against the inconvenience of a total rebuild.

Key

A: Spyware may be present, although perhaps not affecting computer performance.
B: Spyware is almost certainly present, perhaps slowing down computer performance and producing irritating or offensive pop-ups. Viruses, Trojans and worms may be present if the anti-virus and firewall are not updated/configured correctly.
C: Spyware is almost certainly present, perhaps slowing down computer performance and producing irritating or offensive pop-ups. There is a higher risk of finding viruses, Trojans and worms. Computer performance may be affected by malware infection.
D: Spyware is almost certainly present, perhaps slowing down computer performance and producing irritating or offensive pop-ups. Viruses, Trojans and worms are almost certainly present and severely affecting computer performance: the computer may be very slow to respond and internet connectivity may be lost.

1. Privacy, security and protection of data are critical.
2. Privacy and security are critical.
3. Privacy and security are not critical.

Recommended action

	A	B	C	D
1	Clean	Evaluate	Evaluate	Reinstall
2	Clean	Evaluate	Evaluate	Reinstall
3	Clean	Clean	Evaluate	Evaluate

Clean

Clean malware infection and install or upgrade security.

Evaluate

Investigate malware infection. If malware infection, particularly by Trojan horses is found, consider wiping the hard disk and reinstalling the operating system. This may prove to be necessary anyway if malware has damaged the system. Malware infection may be causing poor system performance and even resisting cleaning by disabling certain programs and access to certain web sites. In the case of a minor infection, clean and install security. Proceed with cleaning in cases of a more severe infection only when there there is no option (i.e. no rescue disks) or the security privacy risks are not of concern (i.e. on the kids' computer which is only used for games anyway.)

Reinstall

Security and privacy can only be guaranteed by wiping the hard disk and reinstalling the operating system. It is not worth taking the risk that a hacker has installed a 'backdoor' into the system which might not be found during cleaning. Install security after reinstallation.