Considering how many setbacks Microsoft's defense has suffered so far in this landmark antitrust trial, you'd think the company's legal team would spare no effort to restore its shattered credibility. So what's to account for witness No. 9, Microsoft's Daniel Rosen?

During several hours on the stand on Monday, Feb. 22, Rosen, general manager for new technology, couldn't recall that anyone at Microsoft in the mid-1990s believed that an Internet browser made by Netscape Communications Corp. threatened Microsoft's supremacy in operating systems. His insistence contradicted earlier statements made by himself and other Microsoft officials, including Chairman and CEO Bill Gates.

During cross-examination, Rosen also testified that Netscape was anxious to hand over market leadership in browsers, even though the company was making millions of dollars on the product. He denied having sent an incriminating "draft" E-mail, though the government prosecutor later told him that it was found in the computer of another Microsoft employee. And he quibbled over the definitions of technological terms whose meaning other Microsoft officials had conceded.

ABRUPT END. Rosen was so contentious that at one point U.S. District Judge Thomas Penfield Jackson sighed and looked up at the ceiling. And David Boies, the Justice Dept.'s lead trial counsel, was frustrated enough to cut off Rosen in mid-sentence and abruptly end his cross-examination. Outside the courtroom, Boies said his points regarding Rosen's "credibility had been made."

Justice and 19 state attorneys general are accusing Microsoft of trying to kill off Netscape's rival browser because the software giant considered the browser to be a threat to its Windows operating system. Justice officials say Microsoft proposed to Netscape officials an illegal market-division scheme at a June 21, 1995, meeting, in which Microsoft would sell browsers for Windows computers and Netscape would sell to non-Windows users. Rosen attended the meeting.

Rosen denied that he considered Netscape to be a threat in late 1994 and early 1995, because Netscape CEO James Barksdale and other executives were telling him at the time that "they didn't see themselves as a competitor with Microsoft." He said Barksdale "wanted to structure a partnership with Microsoft" so that Microsoft would build underlying Internet technologies into Windows. That would free Netscape to "provide resources in their core competencies," such as servers. He testified that Netscape no longer wanted to fuss with building basic technologies into its products.

"WREST" OR "TAKE"? The government contends that Microsoft was the one that made such a proposal. By building core Internet technologies into Windows, Justice says, Microsoft would be ensuring that Netscape loses the ability to become a competitor in "platforms," or operating systems, for which developers write their applications.

Boies challenged Rosen's statement that Netscape sought to make the deal. He pointed to a May 15, 1995, memo from Rosen in which he noted that Microsoft should "try to strike a close relationship with Netscape" in which "our goal should be to wrest leadership of the client evolution from them." Software developers use the word client in this context to mean browser.

If Netscape was such a willing partner, asked Boies, "why was it necessary to wrest leadership from them?" Rosen responded that by "wrest," he meant "take." To which Boies said: "Netscape wants to give it to you, and you will just take it." Rosen responded: "Yes." The Microsoft exec also noted that the memo was a draft that was never sent and was riddled with mistakes and with statements that he didn't mean even when he wrote them. After the lunch break, Boies told Rosen that the memo was found in a colleague's computer.

"BILL WAS WRONG." Rosen said he was unaware that other officials considered Netscape to be a competitive threat to Windows, as Microsoft execs Paul Maritz and Brad Chase have already testified. Rosen said he disregarded a statement in a memo written by Gates in May, 1995. His boss noted: "A new competitor 'born' on the Internet is Netscape." Gates noted that Netscape's "multi-platform strategy" could "commoditize the underlying operating system" because developers would be able to write applications directly to Netscape browser code.

To that statement, Rosen testified, "I remember thinking that Bill was wrong" because Barksdale was telling Rosen at the time that he didn't want to compete on the platform. "I remember that I probably had a better perspective than Mr. Gates did," he said.

Rosen will remain on the stand on Tuesday, Feb. 23, to be questioned by Microsoft attorneys. The company's last witness is expected to appear on Feb. 26. Judge Jackson has then ordered a recess until about Apr. 21 so that he and Boies can handle other scheduled trials. When the Microsoft antitrust trial resumes, both sides will present several rebuttal witnesses.

By Susan Garland in Washington