Windows 7: Windows 7 Keeps Asking For (Re-) Activation

I recently upgraded my PC from Win 7 Home Premium to Win 7 Professional, but now every few days my desktop wallpaper disappears and turns solid black, and in the lower right corner I get the message that "This copy of WIndows is Not Genuine" and it then prompts me to re-enter my serial number and re-activate my copy of Windows 7 on-line. Has anyone ever encountered this problem before? Right before this happens I get a cryptic error message to the effect that there has been some change that has called the authenticity of Windows into question. It's pretty annoying to have to keep activating my copy if Windows 7 evety few days. Does anyone have a clus as to why this is occurring and how I might be able to resolve it?

Thanks for any and all advice!

Did you change some hardware after upgrading to Pro? Retail keys get tied to a hardware hash so if you make significant changes, you may get deactivated. But it shoudnt happen off and on.

Random deactivations can happen because of a permissions problem. Follow the steps here.

Genuine Windows 7 Became Pirated? Make It Original and Activated Again - Tweaking with Vishal

I can take a look at your mgadiag log for clues. For that, download mgadiag, run it, click on the Copy tab, paste into notepad, save as .txt file and upload the file here.

go.microsoft.com/fwlink/?linkid=52012

Please call the toll free number to Microsoft and they will re-set your Activation. This should not be a problem if you have a legal copy of Windows 7. -WS

eggs @ play

I did not change any of the hardware. The only change was an upgrade of the OS, as outlined above. It IS a legal copy, as I am MCSE certified and have a TechNet subscription. The Win 7 Home Premium I purchased retail from TigerDirect. The code for the Win 7 Pro was one of the numbers from my TechNet subscription. It hasn't happened for a few days now, so I am taking a wait and see approach. If it happens again I will follow through with your suggestions. Thanks!

right click on my computer and choose properties.

look on bottom and see if
"windows is activated"