FTP daemon stops responding

I have a strange problem with the FTP server on AIX 5.2. During the busiest time of the day, we get intermittent connection failures or timeouts connecting to the ftp server. The only thing clue that I can find is that daemon log shows the following message:

ftpd[52222]: /bin/ls: Resource temporarily unavailable

Has anyone ever seen this error? Is there anything else that I can look at that might help diagnose this issue?

Thanks in advance for you help!

In this case, the "Resource temporarily unavailable" message usually means another ftpd process has a lock on the process id (PID) file.

Are many people using ftpd on this server?

Yes, the FTP server can have many active users at the same time.