Values in sheets gets divided by 10

Excel 2007
Trying to enter a number in a cell in a spreadsheet
(a) opened with the "blank workbook" (new spreadsheet)
(b) created with Excel 2003 and opened in excel 2007
(c) created with Excel 2007 and emailed by someone who isn't having that problem on his Excel 2007 installation

Any number I type in is automatically divided by 10. The only way I seem to be able to prevent this is by entering a decimal point when I enter the number.

Have tried several different formatting options, although in 2007 I can't seem to find how to "uncheck" fixed decimals. Tried General formatting and fixed decimal formatting, and nothing seems to work.

Looked for hidden macros, none show up when I click on View Macros.