Exporting to Excel 2007

Is there any problem exporting to excel 2007? One of our users installed Office 2007 and is getting the error below,

Assuming that ASPRunner is compatible with XLS 2007, is there a way to avoid the message? Thanks a lot
"The file you are trying to open, 'File Name.xls' is in a different format than specified by the file extension. Verify that the file is not corrupt and it is from a trusted source before opening the file. Do you want to open the file now?
YES, NO, HELP"