I have an exp running on a schedule daily as a method to backup our database. Recently I started getting this error:

EXP-00008: ORACLE error 9817 encountered
ORA-09817: Write to audit file failed.
EXP-00000: Export terminated unsuccessfully

I have checked permissions to the audit log file and everything is ok. I have also checked disk space and there is tons. Any idea what is causing this problem?

SYSTEM: Windows 2003 Std. Ed. Oracle 10g R2