I got this error message from my Time Machine backup software:

Time Machine completed a verification of your backups. To improve reliability, Time Machine must create a new backup for you.

Apple support explains this as follows:

Apple has identified an issue on some Time Capsule systems that could potentially make previous backups unavailable. The Time Capsule Backup Update improves reliability of affected Mac OS X v10.6 systems by creating a new backup.

'Creating a new backup' entails wiping the backup disk and creating a new backup from scratch. Backing up of the 400GB data on my harddisk is probably not going to finish before I have to leave with my laptop in the morning, so I will not be backed up while traveling. Furthermore, all previous incremental backups have been wiped, so if I'd want to restore a file deleted a couple of weeks ago, I'm out of luck.

What a beautifully designed paradox!

I'm experiencing more such classical usability problems with Apple products recently. And I'm not even considering upgrading my iPad to iOS 5 after reading beauties such as

"an error occured while backing up this iPad (-48). Would you like to continue to update this iPad? Continuing will result in the loss of all contents on this iPad?"

Almost looks like they had only one guy in QA.