Such problem should not arise while using the recent revisions of the Aspose.Cells API. Please note, the API loads the file in memory as soon as it is opened with an instance of Workbook therefore you do not need to release the file explicitly. Please give a try to the latest version of the API, and in case the problem persists, please provide us a demo application replicating the issue. We will thoroughly evaluate the scenario to assist you further in this regard.