Your product key is invalid

After the IT support guys did a system restore of Windows on one of the computers at the shop, they found that Windows decided to need activation again, but that it wasn't accepting the serial number on the sticker on the side of the computer. I don't know if they forgot to chase it up, or assumed that maybe we had a pirated copy of Windows and didn't want to get involved, but that computer had been warning us for weeks that it needed activation.

When it reached 5 days, I decided to do the activation step. First, I tried putting in the serial number. Invalid. I thought "Maybe when the original activation happened, they accidentally swapped over the serial numbers with the other computer?". So I tried that, and once again it wouldn't accept it. It displayed an "Installation ID" number that I had to give to an operator so they could check whether I had genuine Windows.

So I had to call Microsoft. It was rather painless. The tollfree number connected straight away, I was asked to press 2 to get to Windows activation, and then enter the Installation ID on the phone keypad, six digits at a time. Once that was done, a recorded message told me that it had been installed more times (or on more computers?) than was allowed in the EULA. I doubt that. I HIGHLY doubt that. I don't believe those computers had been activated any other times since they left the Acer factory.

Anyway, I was put through to an operator, who asked me some questions like "Why did you need to reactivate Windows" and "Has this product been installed on more than one computer", and "Was this a preinstalled Windows or did you have to install it yourself". Then I gave her the first six digits of the installation ID and she was able to find the whole number, presumably from when I typed it into the keypad. She gave me another number to type into the Windows Activation program, which worked.

It took about 5 minutes and was rather easy. But I agree that there's some serious problems with Windows activation, if it doesn't accept legitimate product keys and you have to call Microsoft. It's not even like the hardware changed - it was just an in-place system restore!  I had thought that if the operator gave me any hassle that I could say "I have an Ubuntu CD in my hand. Here is the sound of me inserting it into the computer"  and see what happened; but honestly, the process was painless and apart from the pre-recorded message, I didn't feel like I was being treated like a criminal.