Error messages when opening a file

If have a file that I've made on my desktop in Excel 2007, when I try opening up the file on my laptop in Excel 2010 I get the following message..."Error found unreadable content in 'My File.xlsb'. Do you want to recover the contents of this workbook? If you trust the source of this workbook, click Yes. Any idea of why this pops up every time I download this file?

In addition, if I click yes to the above question, Excel goes through a repair process. After the repair process completes, I receive the following message: "Excel was able to open the file by repairing or removing the unreadable content." The removed feature is: Conditional formatting from /xl/worksheets/sheet66.bin part. Does anyone have any idea what this means and how to gid rid of/ fix it so this doesn't continue to happen every time I want to open the file?

Thanks!