if you set your language to german, fdisk is likely to segfault, if you
cope with logial partitions.
Delete a logical partition at the beginning of your extended and add it
later. -> segfault.
This bug must be known and reported, I thought it was fixed months ago, but
it seems that it didn't make its way to the installer.
See also 8767
*** This bug has been marked as a duplicate of 8767 ***