I have "Windows 7 Professional N" from the Dreamspark webstore and Installed it on a new PC. Now when I try to activate it the key is refused with a message: "Please enter a Windows 7 Professional Key". As I copy&pasted the key from the Dreamsparke site I am pretty confident, that the key is valid. Any suggestions?
First, you might need to have to install the Windows N version. A good idea to do this is to download a legit Windows 7 ISO, and then use a file called "ei.cfg remover". This will make the ISO a universal one that will allow you to install any version. Select Windows 7 Pro N then when it ask. Some keys are universal and some keys are restricted to the N/non-N version.
Also, when it comes to activation, you might need to update it before. However, you then run in a moment 22 because it requires a activation to receive certain windows update, and vice versa. To solve this, download "Windows 7 SP1 network & IT administrator installation package" on Microsofts website, and install.
The reason you might need SP1, is because sometimes Microsoft run out of product keys, thus they create a new set of product keys, that are shipped with SPx versions. Thus the SPx product keys are only valid for SPx since non-SPx version do not recongnize the series, and thus you need to update first.
If the activation system says that the key is not valid for activation, and suggest you purchase a new key, select the option "Use the automated phone system to activate". Certain key series, especially OEM and some promo/free keys like "student keys" and such, are banned for online activation and require phone activation.