Excel problem - Not able to Insert rows in excel

Excel file type - .xls
Version - Microsoft Excel 2003
No. Of rows - 65535 or something
Problem faced - Able to insert columns but not able to insert rows
Password protection - Nil
Cells locked - Nil

Root Cause identified
The sender of file has selected all rows upto 65535 or something. In first sight it appears that this file is filled with 20 rows only. Remaining are blank cells. But not able to insert rows. On closely analysing it was revealed that all cells in between row 21 to row 65535 is having white background. Excel thinks, that the white background is a number. So it does not allow to insert more rows. It says when your capacity is 65535 , how can you add more rows beyond range?!

Failure of Delete method
Hence when message appears -  delete rows - then even after deleting rows , we are not able to insert rows. The new rows that appears again takes white background, so this happens. And we think what is happening?

Use Background change method
Simply select all cells between row 20 to row 65535. Change background from white to colourless. Now the file will work. Now insert rows. You will find INSERT ROWS function is working.

How to change background?
Select cells or all rows between 20-65535
Right click
Go to Format Cells
Go to Fill
You will see the 1st square with white background is selected.
Now you click on NO Color.
The colourless background will be now applied.
Now the file will behave as Normal excel file and you will be able to insert rows