"The windows vista home premium key you typed is invalid for activation"

I'm getting this message about 4 - 5 days after re-installing Windows with a valid key at the side of my computer. Wtf is going on? What can I do?

Nvr mind I followed the automated phone system and it activated fine...

yeah its because recovery cds/partitions dont prompt the user for thier key - they have thier own keys (e.g dell ones use a dell volume licencing key, but are locked to dell hardware), whereas the stickers are for retail versions. What happened in the past is people used to then sell the keys on the side of pcs, hence now you must ring up