CSV stands for 'comma-separated values' and is often referred to as a 'Comma Delimited file' or 'flat file'. The file contains a series of text lines organized so that each column value is separated by a comma from the next column's value and each row starts a new line. Here's an example:
Doe,John,944-7077 Johnson,Mary,370-3920 Smith,Abigail,299-3958 (etc.)
A CSV file is a way to collect the data from any table so that it can be conveyed as input to another table-oriented application such as a spreadsheet or database application. The spreadsheet program Microsoft Excel can read CSV files, but keep in mind that it is not technically an 'Excel' file even after opening the file with Excel. It is still simply a 'CSV file', organized as shown above. Excel simply recognizes the .csv extension on the file and 'knows' that it should be able to view it. In addition, once Microsoft Excel is installed on a computer, the default program to open a CSV file becomes Excel (so double-clicking a CSV file starts Excel and attempts to open the file).
If Excel successfully opens the file, the user has the option to create a true Excel formatted file by choosing the .xls file type before saving. If the file is saved in this fashion, then it is no longer a CSV file, and becomes a true Excel (.xls) file.
Not everyone has Microsoft Excel installed on their computer. When those people click 'Open' from the download dialog, Excel will not start and the file will likely display exactly as shown above, ie: a list of rows with the values separated by commas.
Another issue is that a computer may have Excel installed, but for some reason the .csv file type is not associated with Excel, so Excel doesn't know it is supposed to open the file. For those users, it will likely open as shown above. In this case, the user should use the 'Save' button from the download dialog and save the CSV file to a known location on their computer. They can then manually open their preferred spreadsheet program (Excel or other) and choose File, Open, and find the CSV file they saved. All spreadsheet programs should be capable of opening a CSV file in this fashion.
One thing that can cause this is having odd characters in the title of the report. Known characters that can cause problems are / and ?.
If a report has any of these characters in the title, remove them and try the download again.
NOTE: Some users will not experience this problem. It may also be related to the browser used. In I.E. 6, the problem was experienced. I.E. 7 might work ok.
A clue that this is happening is when you Save the file, the File Type defaults to .txt instead of .csv.