Cacti stops graphing particular host

[buckwestern]

I have had this cacti installation running for over 1 year now and every now and then, it just stops graphing particular devices. If I look at the log, the device is still being polled and doesn't report errors. It is giving data back, but the graphs are empty.

Can anyone shed light on this, please?

thanks.

Version 0.8.7

[BSOD2600]

In the document site, follow the debugging NaN guide.