Formatting HDD and USB-stick results in "unknown" file system

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http://askubuntu.com – I am trying to format a new hard disk (and a USB-stick) using GParted. After successfully formatting the drive (to ext2, ext4, ntfs, fat16, whatever), GParted tries to reload the partition data and concludes that the partition type is "unknown". I tried to use testdisk, which also seems to be confused about the state of the drive. It detected a 2GB partition to be 29GB big. Rewriting boot table data, recreating the partition table and others have not worked. What is there left for me to try? (HowTos)