All of worksheet's data is not visible (hidden), upon opening file
 

In Excel 2007, open workbook with 3 worksheets. Per author, only sheet 1 has
data. Sheet 1's data is not visible. Screen (Excel's sheet window) is blue,
no gridlines. Clicking at random in sheet window shows values and formulas in
the "data" line, or bar, above the A, B, C, etc, column headings. Unhide
workbook and unhide worksheet are no help. Ctrl+A and Unhide is no help.

Any idea why the sheet does not display?
--
Zane Lassiter