Ok - a little more information on this problem. We tried creating a new account to use specifically for the api access. We then just shared the docs that we want to export and nothing else with this account. This account can download the list of spreadsheets fine without ever triggering the 500 error. It also works flawlessly in the gdata spreadsheet sample.
This gives us a potential work around, but it would be nice to know why normal users can't access the spreadsheet api. My guess is that the number of documents in an account has something to do with it, maybe causing something to timeout in the request? John
