CannotCreateCustomizationDomainException: Customization could not be loaded because the application domain could not be created

I'm trying to run an Excel 2007 VSTO 3.0 addin we've created. However since installing the ION Trading MarketView Excel Plug-in our add-in no longer seems to load properly and fails with the following error:

Microsoft.VisualStudio.Tools.Applications.Runtime.CannotCreateCustomizationDomainException: Customization could not be loaded because the application domain could not be created. ---> System.IO.FileLoadException: Loading this assembly would produce a different grant set from other instances. (Exception from HRESULT: 0x80131401)

at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck) at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache) at System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) at System.Activator.CreateInstance(Type type, Boolean nonPublic) at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) at System.Activator.CreateInstance(String assemblyName, String typeName, Boolean ignoreCase, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, Evidence securityInfo, StackCrawlMark& stackMark) at System.Activator.CreateInstance(String assemblyName, String typeName) at System.AppDomain.CreateInstance(String assemblyName, String typeName) at System.AppDomain.CreateInstanceAndUnwrap(String assemblyName, String typeName) at System.AppDomain.CreateInstanceAndUnwrap(String assemblyName, String typeName) at Microsoft.VisualStudio.Tools.Office.Runtime.DomainCreator.LoadMafPipeline(AppDomain newDomain, IntPtr hostServiceProvider, AddInInformation info, EntryPoints requestedEntryPoints, OfficeApp officeApplication, OfficeVersion officeVersion, IntPtr& executor) at Microsoft.VisualStudio.Tools.Office.Runtime.DomainCreator.CreateCustomizationDomainInternal(String solutionLocation, String manifestName, String documentName, Boolean showUIDuringDeployment, IntPtr hostServiceProvider, IntPtr& executor) --- End of inner exception stack trace ---

Does anyone have any idea what could be causing this? Any pointers for how I could investigate further?

Thanks, Tom

Here are some tips you may find on web, in order to fix the problem:

1. Reinstall VSTOR

2. Disable other add-ins

3. Install framework 3.5 sp1

4. Fix error in the security configuration on the computer that is running the Visual Studio Tools for Office solution

5. Modify/Disable custom rule of a company's virus software, blocking the .net framework ability to create the 'shadow copy' version of the vsto .dll.

6. Turn on .NET programmability support http://sqlblog.com/blogs/davide_mauri/archive/2010/07/30/powerpivot-not-visibile-in-excel.aspx

7. Move the entire solution to .NET 4.0