Q When I take my laptop out of town with me, I have trouble connecting to my home network when I return. The laptop detects the Linksys router at home and shows five bars of signal strength, but it can't connect to the router. I've clicked the automatic "repair this wireless connection" option, but it doesn't work.

This is even more puzzling because both the router and my laptop appear to be working. My wife's desktop PC and my smart phone with Wi-Fi capability can access the router. My laptop can access the Minneapolis Wi-Fi network's free public-service pages.

To further complicate matters, if I leave the laptop in hibernate mode or shut off for a day or two, I can connect to the home router again. It will continue to work until the next time I return from taking the laptop out of town. Any ideas?

PAUL LINNEE, MINNEAPOLIS

A I think your laptop's wireless settings have been changed by some network you connected to during your out-of-town travels. In order to connect to your home network, you need to change them back. (Why the laptop eventually reverts puzzles me.)

Router maker Linksys offers ways to check out your gear:

•Check the IP address on the PC (it shows if the PC is properly connected to the network).

•Check the wireless settings on the router (they need to match those on the PC).

•Disable the proxy settings (used by an intermediary server in a business network but not used in a home network).

•Ping the router (send it a signal to make sure it's working).

For details on how to carry out these diagnostic tests, see tinyurl.com/nf9saa.

Readers offer advice Passwords: Roger Spitzer of Hollywood, Fla., bought a $39 program to recover his daughter's lost Quicken 2007 password, and he found it so easy he worried that his own password-protected programs were vulnerable to anyone with similar software.

"It took just seconds to hack through the security of a password using a readily available shareware program," he wrote. "Password-protecting files may offer little or no protection if the file falls into the wrong hands. Encrypting files is a better defense."

Backup: Glenn Morris of Windsor, Calif., said his PC was infected months ago with the Trojan.Spaxe (or SpyAxe) malware program I wrote about recently. He reformatted his hard disk to get rid of it, but the process erased his data, too.

"Fortunately I had backed up my hard drive on a DVD just before I had the Spaxe program, so I really didn't lose much. Now I back up every other day on an external hard drive, just in case."

E-mail tech questions to steve.j.alexander@ gmail.com, or write to Tech Q&A, 425 Portland Av., Minneapolis, MN 55488-0002. Include name, city and phone number.