I am using Excel 2007 and am having trouble with certain numbers. The cell formatting is set to general number. When I type in 12-2896 (part number), it gets changed to Jan96. When I check the formatting, it has changed itself to a custom number into a date format. It only does this with a few numbers. If I change the cell to text, it works fine, but I need it to be in number format to interact with my Access 2007 database. Any ideas?

12-2896 isn't a number it's a string.

I stand corrected. The category it uses in the cell formatting is "General". When 12-2896 is entered into the cell, the formatting changes to "Custom" with a date format. Why?

Because when you put something into excel it tries to guess what it it and what you put in looks like a date to excel, just one in the far future.

Either format it as text or use your own custom format of "##-####"