Chatting with friends and family this season with an instant messenger program? You might see an IM offering free shipping on holiday gifts or a link to an electronic greeting card.

Think before you click that link. Many instant messenger viruses, worms, and Trojans are spread when someone clicks a link or opens an attachment in an infected instant message.

To recognize social engineering attacks and help protect yourself from these threats, see 5 steps to help avoid instant message viruses and What is social engineering?

Also, follow our general home computer safety guidelines, which you can find at Microsoft Security at Home and which include the following:

1. Keep your firewall turned on.

2. Keep your operating system and your IM software up-to-date.

3. Use antivirus software.

4. Use antispyware software.

If you believe your computer has been affected, you can contact Microsoft Product Support Services at no charge by calling the PC Safety line at 1-866-PCSAFETY (North America). All customers, including those outside the U.S., can visit for assistance.