Fast Forward's Help File

Q When I use a Windows XP laptop at home, I don't see the same order of wireless networks that a Vista machine shows at the same location.

AMicrosoft says both operating systems are supposed to show available wireless networks in the same order: first "preferred" networks that you've used before, with the strongest such signals first, followed by any other networks, once again sorted in order of declining signal strength.

XP, however, can fail to do so, listing an apparently stronger signal after weaker ones. Lucas Westcoat, a company publicist, wrote in an e-mail that Windows Vista incorporates updates that should yield "more accurate values" for each network's signal strength.

So if you can check on two different computers, go with the Vista machine's report. You can also try any third-party wireless software on the machine, but most of those programs are harder to use than Windows' own WiFi tools.

When I tried to claim one of those $40 digital-TV coupons at the dtv2009.gov site, my browser said there was a problem with its security certificate. Is this site safe?

Yes, but the site was not set up properly. If you type just http://dtv2009.gov, you'll get that error message in your browser, but if you type http://www.dtv2009.gov, everything will work correctly. (You can also order these coupons, good for the purchase of a converter box that will let an analog TV receive over-the-air digital broadcasts, by calling 888-388-2009.)

People at the National Telecommunications and Information Administration, the Commerce Department office behind the coupon program, have said since February that they would fix this problem. That would be a good idea, given all the stories and ads that cite only the shorter form of the site's address.

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 orrobp@washpost.com. Turn to Thursday's Business section or visit washingtonpost.com anytime for his Fast Forward column.