The daylight savings time change shouldn't be a problem - I designed Seqretary to handle time zones well, which is why I implemented time zone handling from scratch - the standard time zone libraries could not do what I needed. There are time zone handling facilities there to handle future features like setting event times based on a different time zone to the one you are in and recurring event based on different time zones, as well as 2 different ideas of "local" time (for travelling).

I don't know what goes wrong with Dallas, but it worked flawlessly for Sydney. However having duplicated the problem it shouldn't take too much time to figure that out.