Dates Converted To Number

[Birendar Waldiya]

Hi , 
 
Can any one tell me why the dates are getting converted as numbers  when I
am trying to read dates  from a xls file .
 
When does it happen that date  are converted to number ??
 
This is realy an issue that  may hampher business  
 
Please guide
 
Thanks 
 
Regards 
Birendar S Waldiya