ORA-00345: redo log write error block

This error occured on Windows Server 2003 while the weekly backup (Symantec) was running.
Anyone have any ideas why this occurred and as possible work areound?

Thanks

Sat Sep 08 04:18:13 2007
Errors in file c:\oraqa\admin\BLUESKY\bdump\bluesky_lgwr_2752.trc:

ORA-00345: redo log write error block 2 count 276
ORA-00312: online log 1 thread 1: 'K:\ORADATA\BLUESKY\REDO01.LOG'
ORA-27072: skgfdisp: I/O error
OSD-04008: WriteFile() failure, unable to write to file
O/S-Error: (OS 5) Access is denied.

Sat Sep 08 04:18:18 2007
Errors in file c:\oraqa\admin\BLUESKY\bdump\bluesky_lgwr_2752.trc:

ORA-00340: IO error processing online log 1 of thread 1
ORA-00345: redo log write error block 2 count 276
ORA-00312: online log 1 thread 1: 'K:\ORADATA\BLUESKY\REDO01.LOG'
ORA-27072: skgfdisp: I/O error
OSD-04008: WriteFile() failure, unable to write to file
O/S-Error: (OS 5) Access is denied.

LGWR: terminating instance due to error 340 Sat Sep 08 04:18:23 2007
Errors in file c:\oraqa\admin\BLUESKY\bdump\bluesky_pmon_2692.trc: ORA-00340: IO error processing online log of thread

Sat Sep 08 04:18:57 2007
Instance terminated by LGWR, pid = 2752
Mon Sep 10 07:55:45 2007

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