The two primary issues plaguing users are a near immediate failure to complete backups -- which usually occurs after around 10MB of data is copied to the destination drive -- and backups that complete but are invisible, making it appear as though the backup was never performed. The first issue is a result of improper formatting on some external hard drives, according to Apple. Some drives ship with a Master Boot Record partition, or a segment of the drive designed to point the computer at the proper location on the hard drive to begin the boot process. Drives with Master Boot Record partitions are incompatible with Time Machine, and Apple says users must first format the drive properly before using the storage devices to back up files. "Apple could have added a simple check to verify that the drive did not have a Master Boot Record partition," Mihalik said. The second issue which results in 'invisible' backups occurs as a result of computer names that include non-alphanumeric characters. The special characters in a computer's name make backups inaccessible and invisible via the Time Machine interface. Mihalik notes that Apple could have blocked all 'illegal' characters that would cause a backup to disappear from Time Machine, preventing improper names. Despite these issues, however, the Ombudsman says the current issues related to Time Machine are few in number. "People look at the messages and think, yeah, there are a lot of problems reported, but [what's there] are only in the tens, or maybe hundreds at the most," Mihalik explained. "That's a very small number compared to the number of people trying out Leopard."