Sony says it sold 4.46 million PlayStation 3 games console in the Christmas quarter (October-December), which was down 9% from 4.9 million units in the same period last year. That's pretty unusual or, I suspect, totally unknown for a successful games machine.

But Sony scored a hat-trick of declines. PSP sales of 5.08 million units were down by 68,000, while sales of the old faithful PS2 more than halved: they were down by 2.88 million units to 2.52 million.

Sales of PSP game sales fell by 2.8 million units to 15.5 million, while sales of PS2 games plunged by 31.2 million to 29.7 million units. The only bright spot was that sales of PS3 games climbed by 14.8 million units to 40.8 million.

Not surprisingly, the games division's sales fell by a third to ¥393.8 billion ($4.36bn), while operating profits fell by 97% to ¥400 million ($4.42m).

The whole company didn't do much better. Sony's revenues fell by 25% to ¥2.15 trillion, and profits by 95% to ¥10.4 billion ($115.6m).

AP reports that Sony "also reiterated its forecast for a net loss of 150 billion yen ($1.67 billion) for the full fiscal year through March — its first loss in 14 years."

"From the second half of September last year, there has been a sudden deterioration in the economy, and with the effects of foreign exchange it has had severe consequences on our business," Chief Financial Officer Nobuyuki Oneda said.

The strength of the yen against the dollar had a devastating impact. Whether it should have been quite that bad is an interesting question. FinanceAsia.com says:

if you delve deeper into the figures, it does not seem possible that currency shifts were the principal cause of the company's losses. Sony's initial guidance for FY08 was ¥450 billion in operating profit, based on an exchange rate of ¥100 to the dollar. According to brokerage CLSA, yen appreciation would have had an impact of around ¥100 billion, meaning a profit of ¥350 billion. Instead, the company is now forecasting an operating loss of ¥260 billion, or a swing of ¥610 billion on top of the currency losses.

People who share this view may want Sony boss Sir Howard Stringer to be replaced.