This is almost certainly to do with the inaccuracies time-handling within the DNN framework. There are many points at which dates can be calculated wrong mainly because DNN does not support DST (since .Net V2 does not). The team have made their best attempt at accuracy, but unfortunately this isn't entirely possible.

I think 1 hour of your inaccuracy could be because of DST, the other hour could be because you are in a different timezone to your server. So could try changing your timezone for the module instance to negate this.

We hope to improve on this funtionality when DNN provides proper timezone support on .Net 3.5. Howevert this is no timeline for this support within DNN at this time.

(This is a copy of an answer Roger has provided earlier)

Hi there,

From this I assume your site timezone is set to Pacific in Admin/Site Settings/Advanved Settings/Other Settings. Are you just trying to change an individual events module to Eastern? I just tried this and didn't have any problem. Are there any errors in the eventlog?

Cheers
Roger