Gaps in Graphs

Hi everyone! I've used Zenoss Service Dynamics with a previous employer, and recently switched jobs where they had no monitoring in place. I built a basic Zenoss Core 4.2.5 VM running within a Hyper-V environment, but seem to be having issues with large gaps in the graphs which is a huge problem obviously. I'm using the most recent versions of the Microsoft.Windows and PythonCollector Zenpacks, along with the NaN Threshold zenpack. I never had this issue with the paid version, so I'm at a loss to figure out how to fix it.

The VM is monitoring 33 Windows systems, with another 23 Ping only. VM has 4 vCPU/8GB RAM committed to it, running CentOS 6.4.

See attached images. Any ideas on how to resolve this would be greatly appreciated.