"UnitRun failed to load or caused an exception"

I have just downloaded ReSharper UnitRun and attempted to install it. The Windows Installer appears to execute correctly but when loading the Add-In with Visual Studio I get the message:

"The Add-in 'JetBrains ReSharper UnitRun' failed to load or caused an exception." And VS2005 asks me if I want to remove the add-in.

Error Message: ]]>
Error Number: 80131600

Having searched all the forums it appears that similar faults have occurred before. The recommended fix (from 2004) appears to be manually moving a selection of files into the private assemblies folder. However, I can't find any of these files, presumably because they are now neatly packaged inside the downloaded MSI file.

Have I just done something wrong, or is there a more up-to-date fix that I need to carry out?

Thank you in advance to anyone that can offer any advice.

Ben