There is a known, unfixed bug with the combination of using certain survey questions in WSS 2.0 or Sharepoint 2003 and trying to export them to Excel 2003 documented in MS KB 828809.
When doing the export, you may receive the following message from Excel:
This list has hidden columns or read-only columns that require data but for which no default value has been specified. Existing rows in this list may therefore be edited, but new rows cannot be inserted.
This same issue exists if you are using WSS 3.0 or MOSS 2007 and still trying to export the information using Excel 2003. Once you try the export with Excel 2007, there are no issues.
Right now, I don’t have access to a 2.0/2003 environment…I would be curious to find out if exporting with Excel 2007 resolves the issue there too which would prove that the issue is with Excel 2003 and not Sharepoint.
Let me know in the comments if you test this out, know the answer, or I will post an update if I get the chance to test it.