I have a document library. People with permissions can access that document library and can also upload documents. But the problem is when they try to create a new document or open an existing one they get the following error:Microsoft excel cannot access the file .... There are several possible reasons:The file name or path does not existsThe file is being used by another programThe workbook you are trying to save has the same name as a currently open workbook.The interesting thing is that this error does not occur when some one is not connected on a domain. We have ISA too, but that does not monitor the internal network communications.The same error occurs on the default zone or the intranet zone (created throught Alternate access mappings)Any Idea anyone.What's Up dude?

When you open Office file stored in SharePoint document library in browser, the office client application is first started, then the Office application communicate with SharePoint to retrieve the file. And the Office application usually run in the security context of current Windows login. When you upload Office documents onto SharePoint in browser, the operation run in the security context of the user you login SharePoint (The Welcome UserName at the upper right of the web page). My questions are: · What kind of authentication do you use for the web applications? · Since you say this kind of error does not occur when someone is not connected on a domain, I think this error occur when someone is connected to a domain. Is this domain the same as on which the SharePoint farm is installed? If not, are there any trusting relationship among them? · And when someone is not connected on a domain, will the Office client application prompt you for username and password? Or do you use FBA with persistent cookie? Gu Yuming TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com