Many years ago, I was summoned to my publisher's office. He was spluttering excitedly over the big story of the day: "Bill Gates is getting married. This will change the IT business for good. Find a picture of this Melinda woman and put her on the cover."

His argument was that the rapacious competitiveness of Gates would rapidly mellow, as the distractions and mundanity of domestic life sapped his appetite and energy for predatory business behaviour. Microsoft, the personification of Gates, would then bumble along aimlessly, making benign alliances and tamely flapping at competitors, even as these rivals grew dangerous and strong.

Of course, all the evidence suggests that marriage does exactly the opposite to a man. Charged with new responsibilities, most are apparently driven to work harder and, as a result, they do better in business.

In the event, my publisher's analysis was not shared by the editors, and Melinda Gates did not make the cover. Nor did Gates's marriage (on the first day of 1994) seem to blunt his laser-like focus.

But the episode did raise an issue that has periodically fascinated Microsoft-watchers ever since: when will the emasculation of Microsoft begin? At some point, so the theory goes, Microsoft's drive and aura of fearsome power will dissipate and the company will become fallible and even vulnerable.

Some said it would come in 1996 when Microsoft was found guilty of monopoly abuse. Observers drew parallels with IBM, whose paranoia about being broken up in the 1970s and 1980s crippled its decision-making and cast a pall over its relationships with customers. In the event, Microsoft carried on regardless.

Around 1998, some thought Bill Gates's decision to hand over the CEO job to his colleague Steve Ballmer would dilute company's strength of leadership and purpose. But they presumably did not know of Ballmer's linchpin role and terrifying competitiveness.

More recently, observers have foreseen the emergence of open source software represents Microsoft's nemesis. Yet Microsoft's response has been classic – fighting Linux with propaganda and huge discounts. When Microsoft announced its annual results in July, there was little sign of weakness. Sales were up 14% to $36.8 billion and net profits up 8.5% to $8.2 billion. That underscored what a huge powerhouse the company still is: its rise in sales alone – at $4.5 billion – was equivalent to half the size of SAP.

With growth on that scale, it is difficult to forecast anything other than greater domination. But further questions of Microsoft's competitive spirit – and its fallibility – have once again been raised. And this time, with very good reason.

In the past five years, Microsoft's astonishing performance has allowed it to accumulate a cash mountain of $60 billion. Yet shareholders know that, given the scope of the markets in which it participates, its growth must slow. Moreover, regulators are bound to limit its ability to expand into new markets through big acquisitions. As a result, Microsoft's share price has remained stagnant.

The company's response: to gild its stock with the promise of the distribution of vast tranches of its wealth in the form of dividends and share buy-backs (worth $75 billion). That will boost the share price, but what will it do for the company's competitiveness?

Its employees drive has always come from the top. But it is also inspired by at least two other important factors. First, Microsoft has remained at a distance from, and at odds with, much of the rest of the IT industry. The persistent attacks on the company from rogue customers, journalists and competition lawyers seems only to have strengthened that spirit. Second, many Microsoft employees have made a fortune from its success in the form of stock options.

But all that is set to change. By recently settling so many lawsuits and forming so many new alliances, Microsoft's "us and them" mentality is being deliberately dismantled; and with the cash-back payments to shareholders Microsoft is effectively telling its staff that the share price will perform well again, regardless of their performance in the field.

In a mammoth email to staff in July, Ballmer attempted to deal with these issues, promising that Microsoft would continue to grow and to innovate. But his tone sounded defensive, as if he was responding to the high profile guru-critics, such as Geoffrey Moore and Nicholas Carr, who have argued that in giving the money back to shareholders, the company is admitting it doesn't know what else to do with it.

No-one should expect Microsoft to become bumbling and uncompetitive, but these changes matter. The once-sharp difference between Microsoft and the rest of the industry might just begin to blur.