this situation comes up all the time when your computer service guy neglects to "activate" your windows install.
the thing to do is go to the "system" page and click the option to activate windows...
when the page loads click the option to "Activate windows online now"
Now it sometimes works, but in my experience even with Windows install packages that I received SEALED the "Activation" has never, I SAY NEVER accepted the CoA, (No, not even once) on Win7
or Vista. (and about 1 out of 3 on XP installs other than Dell computers)
At this point it'll come up with a page of other options
IF the option is "activate by phone" (automated call system) is presented
you'll first be asked which country you are caling from, after that a Page will come up with a phone number on top and a block of numbers at the bottom, there will be NINE blocks of six digits which you'll need to enter with a touch tone phone (or speak the numbers) then you'll be asked a
question "How many systems this copy of windows is installed on?"
I always answer "ONE" (even on volume/educational licenses), trust me on this,,. (it saves additional aggrevation and my precious time...) and after a wait of a few seconds the femals computerized voice wills ay "verified" and then proceed to read you NINE more blocks of six digits which you need to enter, follow the instructions.
But personally I always choose the "Start over" option after typing in the numbers to have the all read over again before I push that "next" button.
the voice then asks "did you receive an error message?" if you didn't you are done.
If it doesn't work you need to call and bitch at them.
when you get a human on the line they will invariably try to rip you off by telling you you need to buy a new CoA... Not true, if you are stubborn and stay on the line you'll eventualy be put through to a technical service
person who will usually (9 out of 10) help you through the process of re-validating your OS.
Remember in the US Microsoft's Stated policy is that the CoA goes to the motherboard, NOT the CPU, not the HDD or any other hardware but the MoBo. So don't let any third world call center operator tell you differently