A feature of Microsoft Excel that gets pretty annoying at times is that it automatically formats any dates that you paste into it, even non-date strings like 1-1. In order to disable this behavior for a single paste in Excel 2007 follow these steps:
1. Select the cells you want to paste into. Right click, select Format Cells and in the Category list select Text.
2. Copy the text that you want to paste. Instead of simply pasting into the cells click on the arrow below Paste in the Home tab. Click Paste Special, then Text, and finally the OK button.