data in date time field used as lookup keeps changing

data in date time field used as lookup keeps changing

my application is here < http://creator.zoho.com/austinpetsalive/volunteertraining/form/8/>;

I have a date and time field in one form. a second form looks up the dates from the first form and gives users a choice of classes to choose. I tried to enter all times as 20:00:00. Everything was fine at first. when I went back to look at the class sessions form, all times showed as 04:00:00. When I changed them back to 20, everything in the signup form was wrong. all times showed as 12:00:00. They still show as 20:00:00 in the sessions form. I copied the application and started over and it happened again. the date may also have changed to the next day at one point. HELP! I need this up and running as soon as possible.
chandra