WHITE PLAINS, N.Y. — A man who was fired by IBM for visiting an adult chat room at work is suing the company for $5 million, claiming he is an Internet addict who deserves treatment and sympathy rather than dismissal.

James Pacenza, 58, of Montgomery, N.Y., says he visits chat rooms to treat traumatic stress incurred in 1969 when he saw his best friend killed during an Army patrol in Vietnam.

In papers filed in federal court in White Plains, Pacenza said the stress caused him to become "a sex addict, and with the development of the Internet, an Internet addict." He claimed protection under the Americans with Disabilities Act.

His lawyer, Michael Diederich, says Pacenza never visited pornographic sites at work, violated no written IBM rule and did not surf the Internet any more or any differently than other employees. He also says age discrimination contributed to IBM's actions. Pacenza, 55 at the time, had been with the company for 19 years.

International Business Machines Corp. has asked Judge Stephen Robinson for a summary judgment, saying its policy against surfing sexual Web sites is clear. It also claims Pacenza was told he could lose his job after an incident four months earlier; Pacenza denies that.

"Plaintiff was discharged by IBM because he visited an Internet chat room for a sexual experience during work after he had been previously warned," the company said.

IBM also said sexual-behavior disorders are specifically excluded from the ADA and denied any age discrimination.

If it goes to trial, the case could affect how employers regulate Internet use that is not work-related, or how Internet overuse is categorized medically. Stanford University issued a nationwide study last year that found that up to 14 percent of computer users reported neglecting work, school, families, food and sleep to use the Internet.

Pacenza was making $65,000 a year operating a machine at a plant in East Fishkill, N.Y., that makes computer chips.

Several times during the day, machine operators are idle for five to 10 minutes as the tool measures the thickness of silicon wafers.

It was during such down time on May 28, 2003, that Pacenza logged onto a chat room from his workstation.

Diederich says Pacenza had returned that day from visiting the Vietnam Veterans Memorial in Washington and logged onto a site called ChatAvenue and then to an adult chat room.

Pacenza, who has a wife and two children, said using the Internet at work was encouraged by IBM and served as "a form of self-medication" for post-traumatic stress disorder.

He said he tried to stay away from chat rooms at work, but that day, "I felt I needed the interactive engagement of chat talk to divert my attention from my thoughts of Vietnam and death."