[ftp21]

Hello,
This is the second thread for this error:

Sometimes LS write this in error_log and no site is available:
2012-09-20 10:45:40.344 [WARN] call nio_read() to clear pending data, ret: 0, errno: 11.
2012-09-20 10:45:40.344 [WARN] Intercomm event: 17, abnormal.
2012-09-20 10:45:40.344 [ERROR] recv_fd() failed, fd: -1, len: 0, errno: 11.
2012-09-20 10:45:40.344 [WARN] call nio_read() to clear pending data, ret: 0, errno: 11.
2012-09-20 10:45:40.344 [WARN] Intercomm event: 17, abnormal.
2012-09-20 10:45:40.344 [ERROR] recv_fd() failed, fd: -1, len: 0, errno: 11.

I use LS 4.1.13 and cPanel how i can fix it?