In short--try deleting your current data folder (backing it up first if necessary) and run a new test session and see if the freshly generated files are more like what you are expecting. You are correct that the Excel data file headers are generated only once--the first time a session is run. Consequently, if *any* changes are made to the structure of the experiment, then the data may not follow the header from that point on. In such cases, clearing the data folder and doing a fresh run ought to generate an Excel file with the correct header for the more recent data.

Also check out the .SAV data file in the byVariable data folder.

And definitely take a look at the Data FAQ in the user's guide, and the Data section in general--it addresses some of these issues and other important stuff that's handy to know. Here is a link to that info online:

http://www.empirisoft.com/medialab/help/data.htm
http://www.empirisoft.com/medialab/help/data_faq.htm

Let me know if that doesn't help. You can also try doing a search for data and save (etc.) under the MediaLab Troubleshooting Forum to see how others have resolved similar issues.

Hope that helps!