Dynamic Data Validation

Hi again,
It looks like I will become addicted to this forum since it provided me with great help.

I searched for a solution for my problem and found tons of useful ideas, but failed to find one that addresses my problem.

I am using a sheet for building phases, each phase starts with a quarter and takes X number of quarters to finish. then the next phase should start AFTER the previous phase is finished.

Example:
Phase 1 starts on 2008 Q1 and takes 4 quarters to complete so it finishes on 2008 Q4. I defined the quarters in a name range called quarters that the user will selct the start of each phase from. I want to be able to excelude the quarters prior to the completion quarters of the previous phase. In my example, the user should not be able to select starting quarter for phase 2 that is prior to 2008 Q4.

Is there a way of doing this through data validation?

have a look at attached
uses a dynamic range for second validation list