These common mistakes can ruin your computer or invite identity theft.

1. Assuming Your Security Software Is Protecting You

Security software is fully effective only when activated and frequently updated. To update most commercial software products, you must pay an annual fee. A recent survey in the US found that nearly half the users polled who thought their software was protecting them hadn't updated it regularly. Software bundled with a new computer requires special attention because its subscription may expire within weeks.

What you can do: Renew the subscription when the software prompts you. Make sure your security software is active when you're online and that it has been updated within the past week or so.

2. Accessing an Account Through an Email Link

No matter how official an e-mail message looks, trying to access a financial account by clicking on embedded Web links is risky. If the e-mail message is fraudulent, a cybercriminal could use the account number and password you enter to steal your identity or empty your bank account.

What you can do: If an e-mail message asks you to update your password, account number, or other information, don't take the bait. Access an online account only by using your existing browser bookmark or typing in the institution's Web address.

3. Using a Single Password for All Online Accounts

Nine percent of home Internet users who responded to a State of the Net survey said they used a single password for all their accounts. That practice lets someone who gets your password and steals your identity easily access all your accounts.

What you can do: Using different passwords need not be burdensome. Do what 15 percent of the respondents to the survey do: Use variations on one password. A well-crafted password uses a combination of at least eight letters, numbers, or punctuation symbols.

4. Downloading Free Software

You couldn't resist that neat, free utility. Or your teenager couldn't resist those fish-tank screen savers and smiley faces. Now your computer runs more slowly than ever. That's because spyware was probably packaged with the freebies.

What you can do: Download freeware only from reputable sites such as SnapFiles.com and Download.com. Free software is often anything but. If you use Microsoft Windows, eliminate most spyware by downloading the free Microsoft Windows Defender and scanning your PC. If you use Windows Vista, there should already be a copy of Defender on your computer.

5. Thinking Your Mac Shields You From All Risks

According to this year's State of the Net survey, Mac users fall prey to phishing scams at about the same rate as Windows users, yet far fewer of them protect themselves with an anti-phishing toolbar. To make matters worse, the browser of choice for most Mac users, Apple's Safari, has no phishing protection.

Phishing is the act of sending an e-mail to a user falsely claiming to be an established legitimate enterprise in an attempt to scam the user into surrendering private information that will be used for identity theft. The e-mail directs the user to visit a Web site where they are asked to update personal information, such as passwords and credit card, social security, and bank account numbers, that the legitimate organization already has. The Web site, however, is bogus and set up only to steal the user’s information.

What you can do: Use a browser with phishing protection, such as the latest version of Firefox or Opera. Also try a free anti-phishing toolbar such as McAfee Site Advisor or FirePhish.

6. Clicking on a Pop-up Ad That Says Your PC Is Insecure

Fifteen percent of respondents to the survey who saw pop-up ads clicked on them. But that's never a good idea. Even if you know such pop-ups are phonies, they're still dangerous. It's easy to click inside the ad by mistake and be transferred to a spyware site or, worse, have malware automatically downloaded onto your computer. The survey showed that 13 percent of respondents who saw such a pop-up tried to close it but launched it instead; 3 percent clicked on a pop-up and got a malware infection.

What you can do: When closing a pop-up, carefully click on the X on the upper left or right corner, not within the window. To avoid pop-ups altogether, enable your browser's pop-up blocker or use a free add-on blocker such as Google Toolbar.

7. Shopping Online the Same Way You Do in Stores

Online shopping requires special precautions because the risks are different than in a walk-in store: You can't always be sure who you're doing business with. You must disclose more personal information, such as your address, to the online retailer. Thieves can sneak in undetected between you and the retail site.

What you can do: Use a separate crdit card just for your Internet shopping, as did 7 percent of respondents to the survey. Don't use a debit card. Sites that display "https" before their address when you'rs entering sensitive information  and those displaying certification symbols from TRUSTe and other organisations are usually sate, but there are no guarantees. When in doubt, get a virtual account number from your credit-card company. It's good for only one purchase from a specific vendor.

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Summarised by the WOUGNET TechSupport team from an article posted on ConsumerReports.org