Bill Gates, the world's richest man and chairman of Microsoft, has accused the United States government of conducting a show trial against his software company in its landmark monopoly case, which is due to re-open in Washington today.

In an extraordinary email exchange with the New Yorker magazine Mr Gates said that the government had turned the case into "a show trial with the primary goal of embarrassing us every day". The trial, which is investigating claims of Microsoft's abuse of its monopoly position, is to resume after 15 months of hearings.

The New Yorker paints a picture of a petulant, often childish man who realised that the government was winning the publicity relations war last December and set about trying to change his company's image.

Some time after Mr Gates had ordered his lawyers to become more accessible to reporters a senior executive allegedly drafted a set of "image attributes" to be pedalled.

Among these were "Microsoft cares about making a difference in my community", "charitable giving improves the lives of many people" and "Microsoft is honest".

A crucial email, setting out Mr Gate's preferred public image for Microsoft and under stood to have been sent in late February, coincided with a frenetic publicity push by the William H Gates charitable foundation which hinted that the Microsoft founder's fortune would be used to rid the third world of disease.

But such an account is unlikely to diminish Microsoft's reputation as an organisation which likes to maintain a vice-like grip on the industry. It details the compilation of dossiers on journalists and a "hardcore" mentality among the 31,000 employees of the company in Redmond, Seattle.

Microsoft and the department of justice are to start presenting their "findings of fact" to Judge Thomas Penfield Jackson in Washington today.

Microsoft is expected to argue that it constantly faces new forms of competition in the fast-changing world of new technology, while the government is likely to say it believes Microsoft's behaviour has represented an abuse of its monopoly position.

This stage of the trial is set to last until September 10, when each side can argue against the other's findings. The judge is not expected to announce his verdict until later in the year.

Although confident that Microsoft's behaviour was normal business practice Mr Gates regrets that the company was unable to settle with the government before it launched its case in May 1998. "I wish we could have settled," he said. "I wished that at the time ... We've always wanted to settle this thing."

Mr Gates is understood to believe that any settlement talks were defeated by the government's desire for Microsoft to seek permission for any new development. In a rapidly changing world such demands could not be acceptable, he said. "You have to have a business left when you settle."

One of the options open to the judge is to break up the company. Chris Shilakes, Microsoft analyst at Merrill Lynch, said last week that the company "could be more dangerous if split into smaller bits".

Mr Gates' latest New Yorker profile offers illuminating insights into the life of the man who dropped out of Harvard to write software, including modelling his engagement party on the Great Gatsby and appearing himself as the decadent central character.

But the notoriously badly coiffed, scruffy multibillionaire can also irritate fellow executives, barking at them: "That's the stupidest thing I ever heard." A man worth $100bn raises eyebrows with behaviour, which allegedly includes "rocking, volatile outbursts and jumping", but also handwrites cards to friends, says the magazine.

Citizen Microsoft

Bill Gates has clearly woken up to the fact that some in the outside world view Microsoft as arrogant and overly sure of itself. He appears to have ordered a fresh set of "image attributes" which have been promptly leaked:

"Microsoft cares about making a difference in my community."

"Its charitable giving improves the lives of many people."

"Microsoft is honest."

"Microsoft is a leader in good corporate citizenship."

"Microsoft is a company I trust."

"Microsoft is a generous and supportive corporate citizen."