gaps in graphs

[bfeole]

I'm not sure where to start with this. I've run snmpbulkwalk on the OID's to figure out which one is the best (which one finishes in the quickest time), and tried increasing the number of collection threads. Is there an error log somewhere I should be checking? There will be gaps for a few polling periods and then it'll return to normal, then another gap, and it just keeps happening, and it appears to affect all graphs. Any help would be appreciated.