Error while running VSTO application from Network path CannotCreateCustomizationDomainException

Environment: VS2008 .NET 3.5 - VSTO runtime 3.0 - Excel 2007

We have published the VSTO Excel document level customization to network path. All our users are able to copy the .xltm file from the network location to desktop(all the assemblies are still in networkpath) and able the run the customizations when the file is opened. When file is opened, it asks for install and user installs and proceed. It works fine. But, all these users are administrators to their machine. But, there is one special case. One of the user is using server machine to use these customizations and he is not an administrator on that machine. When he tries to open the .xltm file, he is getting error

Microsoft.VisualStudio.Tools.Applications.Runtime.CannotCreateCustomizationDomainException:
 This document contains custom code that cannot be loaded because the
 location is not in your trusted locations list: XXXX.XLTM. If you
 trust this document you can save and open it from a location on your
 computer.  For more information, see
 http://go.microsoft.com/fwlink/?LinkId=99104.    at
Microsoft.VisualStudio.Tools.Office.Runtime.RuntimeUtilities.VerifyDocumentIsTrusted(String
 documentFullLocation, String documentName, OfficeVersion
 officeVersion)    at
Microsoft.VisualStudio.Tools.Office.Runtime.DomainCreator.CreateCustomizationDomainInternal(String
 solutionLocation, String manifestName, String documentName, Boolean
 showUIDuri

We added the \networkpath and subfolders to Excel trusted locations, enabled all macros. But, still he is getting the error. I also added th开发者_JS百科e file://networkpath to trusted sites in IE. Still no luck. Still he is getting the error.