Here something that might be a clue I see in your Comma Delimited File: (This is a snip of part of it) Part of the time it shows Wunderground v.1.13, part of the time it shows WeatherLink 5.7. Also notice the upload times. Some are only a minute apart. I don't use the WeatherLink module for uploads either. (I use VWS) It's almost like you have two different modules or leftover pieces of past modules running inside WeatherLink. One time I left VWS running on both my laptop and desktop PCs, forgot to turn off uploads on my laptop, and as I recall I had the weird looking graphs like yours from both programs sending the data.
007-10-21 00:00:00,48.0,46.4,30.26,ESE,111,2,2,94,0.00,,,0.39,Wunderground v.1.13,
2007-10-21 00:06:00,48.0,46.4,30.26,ESE,113,1,1,94,0.00,,,0.39,Wunderground v.1.13,
2007-10-21 00:10:00,48.0,46.4,30.28,SE,135,1,6,94,0.01,,,,WeatherLink 5.7,
2007-10-21 00:11:00,48.0,46.4,30.26,SE,133,1,1,94,0.00,,,0.39,Wunderground v.1.13,
2007-10-21 00:17:00,48.0,46.4,30.26,SSE,160,0,1,94,0.00,,,0.40,Wunderground v.1.13,
2007-10-21 00:20:00,48.0,46.4,30.29,SSE,157,2,5,94,0.01,,,,WeatherLink 5.7,
2007-10-21 00:23:00,48.0,46.4,30.26,SSE,160,1,1,94,0.00,,,0.40,Wunderground v.1.13,
2007-10-21 00:29:00,47.9,46.3,30.27,SSE,160,0,0,94,0.00,,,0.40,Wunderground v.1.13,
2007-10-21 00:30:00,48.0,46.4,30.29,South,180,1,3,94,0.00,,,,WeatherLink 5.7,
2007-10-21 00:35:00,47.9,46.3,30.27,SSE,163,0,1,94,0.00,,,0.40,Wunderground v.1.13,
2007-10-21 00:40:00,48.0,46.4,30.29,South,180,1,3,94,0.00,,,,WeatherLink 5.7,
2007-10-21 00:41:00,47.9,46.3,30.28,SSE,163,0,0,94,0.00,,,0.40,Wunderground v.1.13,
2007-10-21 00:47:00,48.0,46.4,30.28,SE,145,4,4,94,0.00,,,0.40,Wunderground v.1.13,
2007-10-21 00:50:00,47.9,46.3,30.29,South,180,1,4,94,0.00,,,,WeatherLink 5.7,
2007-10-21 00:53:00,48.0,46.4,30.28,SE,139,1,3,94,0.00,,,0.40,Wunderground v.1.13,
2007-10-21 00:59:00,48.0,46.4,30.28,SE,140,4,4,94,0.00,,,,Wunderground v.1.13,
2007-10-21 01:00:00,47.9,46.3,30.31,South,180,1,3,94,0.00,,,,WeatherLink 5.7,
2007-10-21 01:05:00,48.0,46.4,30.28,SW,214,1,2,94,0.00,,,,Wunderground v.1.13,
2007-10-21 01:10:00,47.9,46.3,30.31,South,180,1,4,94,0.00,,,,WeatherLink 5.7,
2007-10-21 01:11:00,48.0,46.4,30.29,South,179,0,1,94,0.00,,,,Wunderground v.1.13,