WASHINGTON (AP) -- Microsoft Corp. confronted a rival computer executive with e-mail Thursday that suggested his company offered in late 1997 to cease work on its Internet browser software and agree not to compete with another company.

Citing the e-mail, Microsoft accused Sun Microsystems Inc., then developing its HotJava Internet browser, of proposing to "unify browser efforts (and) stop competing" with Netscape Communications Corp.Netscape's was at the time the world's most popular browser. HotJava never was sold as a commercial product.

The allegation is significant because one of the government's central claims against Microsoft is that it tried illegally to divide the market with Netscape for Internet software in June 1995, months before Microsoft began offering any browser, the software that lets people view information on the Internet.

Spokesman Mark Murray criticized the government's "irresponsible double standard" in challenging Microsoft's competitive position and called Sun's alleged offer "certainly far more explicit and far more questionable than anything Microsoft discussed with Netscape."

The government said it had no evidence Sun's alleged offer was carried forward, and little information was available about the context of any agreement between the companies.

"The fact somebody else raises competitive problems doesn't get Microsoft off the hook," Justice Department lawyer David Boies said outside the courtroom. "Whatever two companies did doesn't make an antitrust violation appropriate. The everybody-else-does-it defense really doesn't work."

An outside antitrust lawyer, Daniel Wall of San Francisco, said the allegation hurts the government's case.

"This sure looks like the deal the government is complaining about," said Wall. "Each time they have to distinguish away something that walks and talks and quacks like the same thing, their position becomes more and more unappealing."

Microsoft's lawyer, Tom Burt, used the e-mail from Sun employee Karen Oliphant to confront James Gosling, a vice president and one of Sun's top scientists.

In the 1997 message, Oliphant describes "Sun's goals and the key items we would like" from a proposed agreement with Netscape.

The first item reads: "unify browser efforts; stop competing." Another e-mail, sent in September 1997 by Oliphant's coworker, describes Sun's goals with Netscape as "unified browser effort" and "get (Sun) and (Netscape) on one browser."

Gosling testified he was unaware of any deal with Netscape to end Sun's development on its HotJava browser.

But Gosling acknowledged that it was "certainly the case that Netscape wasn't happy about the existence of HotJava." He added, "Certainly they would have been happier if we didn't release it as a commercial product."

A Sun spokeswoman, Lisa Poulson, called Oliphant's e-mail "a proposal by a very junior person" but said the company's HotJava was "never intended to be a competitor." She said it was developed to demonstrate Sun's technology and is now used by Sun employees.

Earlier Thursday, Microsoft belittled Sun's rival computer technology, called Java, suggesting that its troubled early years were Sun's own fault rather than the result of illegal behavior by Microsoft.

Burt confronted Gosling, who helped create Java, with claims that his technology has been overhyped and suffers from critical performance problems and compatibility bugs.

Gosling acknowledged "some rockiness" with earlier versions of Java, a 2-year-old computer language that creates software that can run with only minor changes on a variety of computers, not just those using Microsoft's Windows operating system.

"It is getting better," Gosling said. "We are working to make it better. ... We are not perfect."

As part of its antitrust case, the government contends that Microsoft saw Java as a menace to its dominant Windows operating system because Java programs don't explicitly require Windows.

The government alleges that Microsoft, to protect its Windows monopoly, tried to "pollute" Java by encouraging developers to use a Windows-dependent version, and that it also tried to block distribution of Sun's Java, which was included as part of Netscape's Internet browsing software.