The quick cure for what ails your computer.
Illustration of a computer
Credit: Carey Sookocheff

First: Go off-line. If you suspect a virus has struck your computer―it suddenly starts working very slowly, crashes often, or seems to be doing something even when you aren’t―your first step should be to “disconnect your computer from your Internet provider to keep it from spreading,” says Silas Miller, president of Rent- A-Geek, in Burlington, Vermont.

Then: If you have antivirus software, such as Norton’s or MacAfee’s, run a scan immediately. If the software detects a virus, it will take action to get rid of the virus and notify you when it has. If you don’t have antivirus software (or if yours is out-of-date), call your computer’s manufacturer for phone-based assistance, says Gretchen Miller, director of product communications for Dell. And “if you have a second PC or a laptop, use the uninfected one to get advice from the manufacturer’s website on how to fix a virus,” she says. If all else fails, step away from the machine and call a pro.