PostgreSQL 8.1: createdb: xflush error ?

Hi,

I'm trying to make a new database, yet when I try to do this I get the
following error:

ERROR: xlog flush request 0/827520 is not satisfied --- flushed only to
0/80D7B8
CONTEXT: writing block 5 of relation 1663/16893/1259

Can someone give me a clue of what it means ?

Regards,
Steven