Ok so its only when you log in as a non "superuser" account that the problem happens? To explain a bit about the user attributes - basically what that does is allow you to pass the user's Service Desk userid and password to Service Desk via the data source, so that the data partition constraints for that user are enforced when the data comes back from Service Desk into the Jasper report. In order to set that up, you would have to have each user created in Jasper under the servicemanagmeent organization, and then you would need to have each user log in and run the Service Desk User Authorization report, which would then populate the attributes with the Service Desk userid and password for that user, on that user's jasper account (thus it can then be passed to the data source when that user runs reports).
However, in your case, since its only happening to this one report, that seems to not be the problem here because it would affect all reports - and you should be able to run any report as any user if the data source is set to log into SDM as the "servicedesk" account. SO, I dont think you need to set up the user attributes to fix this one. Its really odd to be honest - strange that when logging in as a user other than superuser, that you can run all other reports but this particular one. I would check the jasperserver.log file at the point when it hangs on that report. See if there are any error messages in there and share the snippet of the error here if there are any.
Let us know,
Thanks,
Jon I.