DuoMark International has released a program designed to protect PCs from unreliable or malicious software.

9Lives prevents programs from infecting PCs with a virus, corrupting data files, or causing unwanted configuration alterations by shielding all data files from modification, company officials said.

The program allows users to switch to "Protected Mode," which shields all data files on the computer's hard drive. The user can then install new applications, change operating-system settings, or perform any other standard PC operation, with the assurance that the machine can be returned its original configuration. If the operating system becomes corrupted, 9Lives presents a menu before the operating system loads, allowing the user to throw out the changes and restore their original configuration, even if the PC cannot reboot.

A trial version of the program, which allows five "Protected Mode" sessions, is available at www.duomark.com/9Lives . Single-user licenses may be purchased for $49.95 from DuoMark's online store at www.duomark.com , with an introductory 20 percent discount through Aug. 15, 1999.