PANIC: could not write to log file 0

Hi All -

I am using PostgreSQL 8.1 which came packaged with WS_FTP Server 6.
The PostgreSQL service has died on me a few times over the past week
and Ipswitch support has been no help. I found the following in the
PostgreSQL log each time this happens. Might anyone have some
suggestions on how I can resolve this?

Thanks much -Isaiah

2008-07-23 23:06:16 PANIC: could not write to log file 0, segment 29
at offset 4915200, length 16384: Permission denied

2008-07-23 23:06:16 STATEMENT: UPDATE Host_Users SET
User_Failed_Login_Count = 0 WHERE (UserID = 4)

This application has requested the Runtime to terminate it in an
unusual way.
Please contact the application's support team for more information.

2008-07-23 23:06:16 LOG: server process (PID 2100) was terminated by
signal 3