Hi,
Try to play with "GetUtcTime" function. Here is example for NAV to CRM "Requested Delivery Date" mapping:
CRM Requested Delivery Date = If(LessThan(Sales Order LinesSales Order LineRequested Delivery Date, Date(1900, 1, 1)), Date(1900, 1,1), GetUtcTime(Sales Order LinesSales Order LineRequested Delivery Date))
I described this issue while ago over here www.nav-connector.com/.../Issue-with-Dates-when-you-sync-from-NAV-to-CRM-direction.
Cheers,
Konstantin
P.S. this message copied from my answer to you on mibuso (you're not replied there if it works for you or not)