I now realize that this leaves personal data open to anybody using my PC, because the program does not offer password protection for files. Try encryption software that turns data into code that only the CIA would be able to break. There's PGP, or Pretty Good Privacy, the granddaddy of protection software. It was developed to let people encrypt their e-mail, but it works with data files as well. Then there's E-Z Crypt, which offers a trial version.
Some experts recommend compression utilities.
These condense files to save hard-drive space and are not, strictly speaking, encryption programs. But some, including WinZip, let you protect compressed files with a password and coding. The encryption will defy most computer users, but it is not up to the tough standards set by PGP and others. Every time I restart my PC, I get a message saying I am using System Configuration Utility and selective startup to troubleshoot my system. So if you suspect a program is causing problems, you can use the utility to stop, one by one, your programs from loading until you find the culprit.