Problem with Excel 2000 Shared Workbooks
 

I know this may seem like an idiotic question..but can anyone suggest how I
can resolve the problem with blank cells when Excel resolves conflicts ?

If the cell from previous entry is blank, and simalteneously another user
enters non-blank value into the same cell, Excel does not seem to recognize
this to be a conflict, and simply accepts the non-blank value in that cell .
Is there anyway to overcome this problem ?