Calendar Entries

We currently upgraded to Notes 6.5 from 4.6. Our Admin Server is 4.6, which runs the 4.6 client and we replicate databases from this server to our 6.5 servers, which have the 6.5 client. We are currently exeriencing problems with calendar entries and time zones. We have users in our TX office who are runing the notes 6.5 Client based on our NY server, which is also running Notes 6.5. When they do calendar entries for all day events, the entries are showing up on the correct day and also the day before. Is there a setting that would stop this from happening?

Any help is greatly appreciated.

Thanks!

Christine