[Xymon] Historical data not available

I've noticed that a lot of times when I try to click on one of the historical status pages in Xymon, I get a message that says "Historical status log not available". This even happens for very recent historical pages.

Then I looked at the history.log file and saw a whole bunch of these messages:

      2012-03-16 12:06:31 Historylog directory

/export/home/hobbit/data/histlogs has less than 5% free space - disabling save of data for 5 minutes

But /export/home/hobbit/data/histlogs has plenty of free space left:

      (hobbit)@hobbit:~$ df -h /export/home/hobbit/data
      Filesystem Size Used Avail Use% Mounted on
      /dev/md/dsk/d30 7.9G 4.0G 3.9G 51% /export/home

Anyone know what's going on?

Thanks, Ray