Has anyone had any problems when setting the datasource of a crystal report to be a dataset?

We have a number of reports where the SP returns a dataset and then this is passed to the crystal report. This works fine on the majority of the PC's, but we have some which, when the report is to be displayed, prompts for database login details. If we amend the report to pass in each table of the dataset then it works ok.

Is there any reason why this would happen on some pc's and not others, when they seem to have the same setups?

Thanks
Steve