The blank spot in the graph indicates that no data was being collected during that period. This happens if the trace is stopped, and then resumed, or if the data is saved, then PingPlotter is closed and reloaded.

The ideal situation is really to have a data collection period running all day, and then to have the customer make note of the times of outages. If they save the data to then send you, you want to make sure they keep tracing - they might be stopping it to send data to you, and then resuming during the next outage (and possibly missing the next outage). You want to make sure they were collecting data during the period of the outage.

The periods of 500 ms might be causing problems with Citrix. I've heard reports of that - 500+ ms latencies can cause disconnects in Citrix.

If you want to email a copy of the data files to support@pingplotter.com, I'll have a look at them.