If you are outputting coldfusion query data to a spreadsheet and you have an error on your spreadsheet that affects layout or cell creation you will not be able to open the spreadsheet.
The OPEN/SAVE/CANCEL bar at the bottom of the browser screen will not go away either until you close your browser. The bar gets stuck.
An error is thrown if you review the CF error logs.
Example: Invalid fieldname
<td>#firstname#</td> vs <td>#first_name#</td>
Underscore is missing so CF goes into error mode but does not display an error on screen.
You may need to use CFTRY CFCATCH around spreadsheet output to see the error if you can not review error logs. You can also remove the CFCONTENT and CFHEADER tags to view the error on screen, but you may want to limit your record quantity output.