I am running Windows 7, 32-bit version.
Today I have tried to re-run de Atmel Studio installer in Admin-mode, but that has not helped me yet.
I use Microsoft Security Essentials for virus scanning.
I see I may have to disable the real-time protection in that, I have not tried that yet.
I will have another go at this on Friday, for the moment I don't have time to work on it.
At least you have given me a clue to what else I can try.