Q I recently found some pictures and e-mails in my files that I don't recognize, some of them pornographic.

This comes about three months after I had to cancel two credit cards that were used fraudulently.

Is it possible for someone to enter my computer and try to assume my identity? I change my passwords every few months.

BRUCE EVERHART, BANNER ELK, N.C.

A I think someone online has taken control of your PC and is using it to relay pornographic spam, probably to disguise the original source.

If that's the case, your credit card numbers could have been stolen if you typed them on the PC while shopping online.

To fix your PC, start your computer in Windows "Safe Mode," which allows only a few trusted programs to run.

To do that, turn off your PC, then turn it on and press the F8 key several times until you get a black-and-white screen that says "Advanced Boot Options." Use the arrow key to highlight "Safe Mode with Networking" and press the Enter key.

Now download and install the Malwarebytes program (malwarebytes.org), and run the update portion so you have the latest list of online threats.

Then restart your PC, and use the F8 key to reach Advanced Boot Options, then Safe Mode with Networking. Run a full PC scan with Malwarebytes, and when it's complete choose "remove selected."

Next, make sure your firewall and antivirus software is up to date. Then wait and see how your PC behaves.

If you have more problems, try running a "Registry cleaner" program that will scrub remnants of malicious software from the PC's Registry, a database of settings. Registry-cleaner programs, some free, can be found at tinyurl.com/ydehzg2.

Q I recently upgraded my Windows Messenger software to the 2011 release, and now I can't make video calls to my daughter. I'm using Windows 7. What can I do?

ED BOLDT, Ottawa

A I suspect your daughter is using an earlier version of Windows Live Messenger that is only marginally compatible with the new Messenger 2011.

If her PC also has Windows 7, ask her to upgrade to Messenger 2011 (tinyurl.com/2fswsyb) as you did, and you should be able to make video calls to her.

If her PC uses Windows XP or Vista, you should both use an earlier version of Messenger that runs on all three operating systems. Find it at tinyurl.com/24f2vwv.

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