Legacy Cumulus 1 release 1.9.4 (build 1099) - 28 November 2014
(a patch is available for 1.9.4 build 1099 that extends the date range of drop-down menus to 2030)
Download the Software (Cumulus MX / Cumulus 1 and other related items) from the Wiki
Discussion and questions about Cumulus weather station software version 1. This section is the main place to get help with Cumulus 1 software developed by Steve Loft that ceased development in November 2014.
You were previously running a 1.9.1 beta (one more than 30 days old). I think you're OK going back to 1.9.0 with the same data, but no guarantees, I'm afraid. Were you somehow unintentionally using the beta?