Welcome to the community! Are you using the WMI Core ZenPack or the new one
that is in beta? If you're not sure, you're using the Core ZenPack version
one.
How many WMI devices are you monitoring? Have you enabled the watchdog
feature for the zenwinperf daemon? What OS are you monitoring with WMI,
virtualized Server 2008r2?
The issue is most likely that the zenwinperf daemon is dying due to issues
with monitoring WMI of your servers.