0 appears when typing 8 in cell

When a customer of mine types an 8 in a cell in a worksheet, it appears as a 0.
She sent the sheet to me and I am able to type 8 without any problems.
She also stated when she has an excel file sent to her, if there are 8's in any of the cells, they appear.
But, if she attempts to update these cells, whatever number she types appears as a 0.
She does not appear to have this problem with any other application.
Any help would be appreciated.