What to Do If Your Computer Is Infected

There are a number of symptoms which indicate that your computer has been infected. If you notice "strange things" happening to your computer, namely:

• unexpected messages or images are suddenly displayed
• unusual sounds or music played at random
• your CD-ROM drive mysteriously opens and closes
• programs suddenly start on your computer
• you receive notification from your firewall that some applications have attempted to connect to the Internet, although you did not initiate this, then it is very likely that your computer has been infected by a virus.

Additionally, there are some typical symptoms which indicate that your computer has been infected via email:

• your friends mention that they have received messages from your address which you know you did not send
• your mailbox contains a lot of messages without a sender's e-mail address or message header

These problems, however, may not be caused by viruses. For example, infected messages that are supposedly coming from your address can actually be sent from a different computer.

There is a range of secondary symptoms which indicate that your computer may be infected:

• your computer freezes frequently or encounters errors
• your computer slows down when programs are started
• the operating system is unable to load
• files and folders have been deleted or their content has changed
• your hard drive is accessed too often (the light on your main unit flashes rapidly)
• Microsoft Internet Explorer freezes or functions erratically e.g. you cannot close the application window

90% of the time the symptoms listed above indicate a hardware or software problem. Although such symptoms are unlikely to be caused by a virus, you should use your antivirus software to scan your computer fully.

What you should do if you notice symptoms of infection

If you notice that your computer is functioning erratically

1. Don't panic! This golden rule may prevent the loss of important data stored in your computer and help you avoid unnecessary stress.
2. Disconnect your computer from the Internet.
3. If your computer is connected to a Local Area Network, disconnect it.
4. If the computer cannot boot from the hard drive (error at startup), try to start the system in Safe Mode or from the Windows boot disk
5. Before taking any action, back up all critical data to an external drive (a floppy disk, CD, flash memory, etc.).
6. Install antivirus software if you do not have it installed.
7. Download the latest updates for your antivirus database. If possible, do not use the infected computer to download updates, but use a friend's computer, or a computer at your office, an Internet cafe, etc. This is important because if you are connected to the Internet, a virus can send important information to third parties or may try to send itself to all email addresses in your address book. You may also be able to obtain updates for your antivirus software on CD-ROM from the software vendors or authorized dealers.
8. Perform a full system scan.