Reactivate Button Freezing Unity

I got a Pro license key and wanted to upgrade from the previous license. I went ahead and clicked the “Enter Serial Number”->Reactivate buttons. Every time I click the “Reactivate” button Unity instantly freezes. I can’t see the cursor over the window and it doesn’t appear to be doing anything.

Try manual activation. See Manual/Offline Activation of Unity 3.x - Questions & Answers - Unity Discussions.