AThis virus (sometimes called Downadup) has been infecting Windows computers for the past several months. It's an exceptionally persistent, aggressive threat. It can spread over shared flash-memory drives, and the most recent variant even blocks access to Web sites of security-software vendors. (If you can't reach http://microsoft.com, your PC is in trouble.)  On April 1, copies of Conficker may download extra-malicious code -- to do what remains unclear -- so you'd better make sure your PC is clean before then.  The Internet Storm Center, a project of the Bethesda-based SANS Institute, maintains a list of links to Conficker-removal tools from numerous security-software developers (http://isc.sans.org/diary.html?storyid =5860). Since Conficker can stop you from getting to that page and those links, you may need to borrow an uninfected machine to download a removal tool. Some vendors also have set up alternate Web addresses that Conficker doesn't know about; for instance, try http://fsecure.com or http://bdtools.net for free Conficker fixes from F-Secure and BitDefender.  Of course, if you've set Windows to install Microsoft security patches automatically and have kept your anti-virus utility current, you should be safe. So if you haven't been downloading those updates, now would be a swell time to start.  My four-year-old laptop's screen has gone almost completely dark. Can I fix that?  The small fluorescent backlight inside the screen has broken or burned out. A computer store should be able to replace it, but that can easily cost several hundred dollars. You may find that it makes more sense to scrap the old computer and buy a new one.  Rob Pegoraro attempts to untangle computing conundrums and errant electronics each week. Send questions to The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or robp@washpost.com. Turn to Thursday's Business section or visit washingtonpost.com anytime for his Fast Forward column.
Q: How can I tell if my computer has been hit by Conficker? How would I remove it?