Phil Goldman, a Silicon Valley engineer who co-founded WebTV, died Friday, according to the Santa Clara County coroner's office. He was 39.
The cause of his death may take several weeks to determine, the coroner's office said.
Throughout his career, Mr. Goldman worked on the cusp of technology and consumer electronics at firms such as Apple Computer and Microsoft Corp.
In 1995, along with former Apple colleagues Steve Perlman and Bruce Leak, Mr. Goldman co-founded WebTV Networks, which allowed users to surf the Internet from their televisions.
Microsoft bought WebTV in 1997 for $425 million and today is called MSN TV.
Last year, Mr. Goldman founded Mailblocks, a Los Altos company that sells a Web-based e-mail system that promises to eliminate unwanted e-mail. In 2003, it sued competing companies using similar technology against spam, claiming patent infringement.
Mr. Goldman held 19 US patents for inventions.
He served on the board of BraveKids, a charity that helps families of severely ill children.