Apple customers are complaining that iCloud, one of the key features of the new iOS5 mobile operating system launched on Wednesday, is not working properly.
ICloud is a cloud-based storage service that the firm first revealed in June. It integrates with Apple hardware so users can sync content across all their Apple devices.
Apple said on its iCloud status page that "users may experience intermittent slowness when logging in to iCloud", but that normal service will be restored as soon as possible.
The firm has also apologised to users experiencing problems syncing specifically their Mail and Notes apps across devices.
Just hours after Research and Motion announced it has fully restored the service to BlackBerry users, angry phone users once again took to Twitter to complain.
However, Apple users appear to be more understanding of the iCloud problems than BlackBerry users were when RIM problems started to emerge.
"Naturally, Apple has an iCloud status page. And naturally, after a massive launch like this, some services are down," tweeted David Chartier.
"OK. I'll [sic] think I'll just switch off iCloud Mail for a couple of hours. Bit annoying when you run your business on it though," added Twitter user Don McAllister.
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