@John: thanks for posting the update. Indeed it has come to my attention that the firmware had a bug that affected a small number of OpenSprinkler 2.1 units that use MCP7940 real-time clock (RTC) whereas the majority of OpenSprinkler units use DS1307 RTC.
This was first discovered by a user who reported the fix in blog comments:
http://rayshobby.net/modified-arduino-ds1307rtc-library-that-also-works-for-mcp7940n/#comment-128196