After updating 1.8-pre1 to 1.8-pre2 I got some problems with chunk loading.
Some of the chunks just never get loaded. It spreads like a disease, more an more chunks get corrupted with every server-restart.
Downgrading to 1.7.10 did not fix the missing chunks, so this bug probably corrupts the world files.
Server-log and Screenshot of the issue included.
Temporary fix: Tried it 3 more times with my backup, third one has no problems.