The company said Friday that it has run out of iMacs.
In a statement, Apple said it had stopped taking orders for the current generation of iMacs and expects its inventory of these machines to run out in the next few weeks.
It also said that its new version of the iMac won't be ready until September, two months later than planned. Many industry experts expected Apple to unveil a new iMac at its worldwide developer conference in San Francisco this week.
"We planned to have our next generation iMac ready by [this] time. ... But our planning was obviously less than perfect," Apple said in a press release. "We apologize for any inconvenience to our customers."
The error in planning comes at a particularly bad time for the Cupertino, Calif., computer maker, because it means Apple won't have a current model for its core markets — schools and universities at the beginning of the back-to-school shopping season.
Overall sales are likely to suffer, because Apple won't have a consumer-oriented desktop computer available for much of the current quarter, which ends in late September.
The delay is another problem for Apple's computer division, which steadily has been losing market share. Apple sold just 1.7 percent of the world's personal computers in the first quarter, down from 2 percent in the first quarter of 2001.
In the first quarter of this year, Apple shipped 217,000 iMacs, down 15 percent from 256,000 units in the same quarter a year earlier.
In reaction to the news, Apple shares dropped significantly Friday, sinking $1.24, or 3.8 percent, to $31.06 in midday trading on the Nasdaq Stock Market.