Hi Frank,

my crystal ball tells me it might have to do with incorrectly mounted file systems (i.e. read-only instead of read/write, most probably the /var file system) - is there anything reported during boot that might hint at such problems?

Have you tried turning it off and on again? Just kiddin', what I really want to know is if this behavior is consistent across multiple reboots... file system errors often are fixed by automatic "fsck" runs during boot, but it might be that either multiple runs are required or that other problems arise, that are "fixed" later on during boot, but some earlier service didn't catch. Upon the next boot, things might be (basically) in order right from the start, giving all processes a chance to operate normally. If the error persists reboots, some deeper cause needs fixing.