After a crash with an OEM Vista laptop, and a reinstall from a Vista disc, the validation failed. Got through to MS who refused to validate it and suggested I called the manufacturer. This I did - the only option they gave me was to purchase another disc and key for 30 quid. Googled the probelem and, reluctantly, cracked the problem. No hardware had been changed on the machine, so this refusal to validate seems a bit odd to me.