Does anyone have a solution for resolving date and time conflicts?

Here's what I mean. In a portal I'm displaying a series of collected timestamped events for an employee (Time tracking). This is the administrative view that allows an admin to edit, add or delete entries made by the employees. Being the feature it is, the admin could accidentally enter or edit an entry that overlaps the time value of another entry. Now I don't want to prevent that but I do want to display the result (conditional format) and draw attention to the conflict.

Each record has a start and stop timestamp and the total time as the difference between the stop and start.

I have to be able to alert the admin if an entry goes outside the "clock in/out" times or overlaps another task.

Conflicts are easily show by multi-criteria non-equi relations, but weren't it better to show a portal of possible:

http://www.nightwing.com.au/FileMaker/demos7/demo705.html

--sd

You might be right but I'm a portal fanatic and prefer to keep my users a layer away from the data.