Incorrect date/time on Yun

I have several Yus on my local network running 24/7. One of them, and only one, consistently has the wrong date and time. For example at the moment it thinks it is "Wed Oct 5 09:55:45 CDT 2011". The other Yun's have the correct date and time. Based on the admin interface NTP is configured (see attached). If I do a ps command the NTP daemon is running and seems to have the same parameters as the other Yuns

1399 root 1496 S /usr/sbin/ntpd -n -p 0.openwrt.pool.ntp.org -p 1.openwrt.pool.ntp.org -p 2.openwrt.pool.ntp.

Any ideas how to fix this? I could set the time manually but the clock will start to wander without NTP. Since this Yun does logging I need pretty accurate time stamps.

I noticed my Yun takes a little time to synchronize to the real time. After it connects to wifi i wait a little bit, less than a minute and then it has the right time.

This Yun has an Ethernet connection and has been up 26 days.

roadfun:
I have several Yus on my local network running 24/7. One of them, and only one, consistently has the wrong date and time. For example at the moment it thinks it is "Wed Oct 5 09:55:45 CDT 2011". The other Yun's have ::::SNIP::::

@roadfun,
Is this time drift? or is it incorrect time set? If the later, then have you tried running ntpd by hand (on the command line) ?
Jesse

Replace busybox-ntpd with standard ntpd which support time drift which Jesse asked.

http://forum.arduino.cc/index.php?topic=222912.msg1626066#msg1626066

ntpq -p
    remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
+ntp2.h.vporn.co 173.13.85.5      2 u   65   64   37   57.814   -9.849   2.276
+host2.kingrst.c 208.75.88.4      3 u   61   64   37   40.626   -6.173   5.317
-services.quadra 121.130.110.69   3 u   61   64   37   81.499   -1.507   3.616
*repos.lax-noc.c 216.218.254.202  2 u   68   64   37   79.674   -2.960   3.111