What version are you using? Since you posted in this category, I assume an old version of DT Reg. The newer releases for 1.5 have improvements for this issue with built-in back buttons in DT Reg to make sure data is retained. It's hard to control things when people are using the browser back button.
This is a complex site with many components, not all of which are easily upgradable to 1.5. Thus the reason for staying on 1.0.15.
The implication that we should just upgrade to 1.5 to fix a software flaw is not a feasible alternative. We really need a bugfix that will work in 1.0.15.