Monday could be D-Day for your computer, but then again, we’ve heard that before.

Monday’s threat is a malware virus called DNSChanger, which threatens to lock out tens of thousands of people from Internet access. It may also search out private information.

“It is impossible to say how many computers are infected in the Philadelphia area. The only thing we do know is that the US has one of the largest base of infected computers,” said Fred Robinson of Waterdog Computer Works in Wayne.

According to the FBI, the trojan virus will divert users from legitimate ISP servers to malicious sites that will alter their Domain Namer Server- the unique address of your computing device. Without access to the correct DNS and DNS servers, you would not be able to access websites, send e-mail, or use any other Internet services.

A Huffington Post report citing FBI data estimates as many as 277,000 computers infected worldwide and about 64,000 in the United States.

What To Do

“A free tool that we use at our shop is from Kaspersky labs and it is called “tdsskiller”. This is a free utility that when run can find the variant of the program and remove it,” Robinson said. “This tool will check for it and also remove it if it is found.

• The FBI has set up a website with instructions and safe links to check your computer for the malware at http://www.dcwg.org.
• The FBI site shuts down just after midnight Sunday at 12:01 a.m. EDT, so don't wait!
• If your cable company is your ISP, check their sites for instructions. Click here for links to the pages Verizon and Cablevision have set up for their customers
• If the virus hits your computer, you will have to manually reset your local DNS settings then make sure your computer is clean at http://www.dns-ok.us

Has your computer ever been hit by one of the big computer viruses? Tell us about it in the comments.

Experts predict malware attack on personal computers, portable devices and laptops, even smartphones will increase by the end of the year.

Antivirus software developer Trend Micro estimates more than a dozen malicious apps were downloaded more than 700,000 times from Google's popular mobile app market before they were removed.