Hi,
Every morning for the last 3 days around 5 AM we have production Instance crash due to following errors from Alert log:

ORA-00221: error on write to controlfile
ORA-00206: error in writing (block 3, # blocks 1) of controlfile
ORA-00202: controlfile: '/u05/oracle/gvr1/gvr1/control03.ctl'
ORA-27072: File I/O error
IBM AIX RISC System/6000 Error: 22: Invalid argument
Additional information: 7
Mon Jun 12 06:14:01 2006
CKPT: terminating instance due to error 221
Instance terminated by CKPT, pid = 6472600

We had no recent changes in Oracle or on OS level. Database was up for at least 7-8 month without any big issues.

If anybody could give me some help on this would be great!

Eugene.