Cupertino firm Apple acknowledged there's been a problem supplying 27-inch iMacs altough it has refused to reveal what the difficulties delivering are.
Nor will it confirm that delays in shipping the 27-inch iMacs are to do with technical problems including hard drive crashes and faulty displays.
While Apple is still supplying the iMac 27-inch model, it is giving shipping times of two weeks for the products. There is no such delay with 21-inch models - they can be supplied in 24 hours.
According to this web site, quite a few people have had problems with machines, largely drawn from Apple's discussion forums.
Apple, according to the same website, says that Apple is changing the graphic card that ships with 27-inch iMacs.