Illinois State Police are warning of a scam involving your computer system.

Scammers will place an alarming pop-up message on your computer or set up fake websites – all to convince you that your computer is infected.

The pop-up screen makes it appear your computer is locked and provides a number to call. Scammers try to get you on the phone and then work to convince you there’s a problem.

They then ask you to pay them to fix that non-existent problem.

If you get a pop-up message that tells you to call tech support, ignore it. There are legitimate pop-ups from your security software to do things like update your operating system.

But do not call a number that pops up on your screen in a warning about a computer problem. If you get an unexpected or urgent call from someone who claims to be tech support, hang up.

Don’t rely on caller ID to prove who a caller is. Criminals can make caller ID seem like they’re calling from a legitimate company or a local number.

If you’re concerned about your computer, call your security software company directly – but don’t use the phone number in the pop-up or on caller ID.

Instead, look for the company’s contact information online, or on a software package or your receipt. Never share passwords or give control of your computer to anyone who contacts you.