You had some kind of communication problem with the station which started here:
26/09/2012 04:01:03.235 : VP2: LoadCurrentVantageData_V, error = -32701
26/09/2012 04:02:00.985 : *** Data input appears to have stopped
26/09/2012 04:02:03.079 : VP2: LoadCurrentVantageData_V, error = -32701
The error code is the Davis DLL saying it was unable to read the data from the console.
This continued for several days until
04/10/2012 06:58:00.771 : *** Data input appears to have stopped
04/10/2012 06:58:06.443 : VP2: LoadCurrentVantageData_V, error = -32701
at which point it appears you rebooted the PC and the Davis DLL was once again able to read data from the station.
So Cumulus didn't get any data from 04:00 on the 26th Sept until 07:00 on the 4th October, so it didn't do the daily rollover on those days.
You have your Davis logger set to an interval of 30 minutes, so it will still have the data stored that you've missed. You can recover by copying the files from the backup it created here:
22/09/2012 17:21:37.000 : Creating backup folder C:\Cumulus\backup\20120922172137\
into the Cumulus data folder (with Cumulus stopped) and deleting the Oct12log.txt file. When you start Cumulus, it will catch up using the data from the logger.
Incidentally, you have the station logger set to 30 minutes, and Cumulus set to 10 minutes, so you are likely to hit this issue:
http://wiki.sandaysoft.com/a/FAQ#Cumulu ... t_start_up, and did indeed hit it on almost all of your recent start ups.
Your forum profile says you have a WS2300?