Try to delete the C:\Users\USER_NAME\Adobe Flash Builder 4.7 Or rename it, then launch Adobe Flash builder 4.7 this should fix the problem I had the same problem a while ago
Thanks for your help but the problem persists.
This may very well not be your problem, but after I downloaded FB 4.7 and messed with some things I had this same issue (Windows 7).
Turns out it was looking for the last workspace it used (since I don't have "Ask for workspace on startup" checked) and because I moved the folder, it couldn't find it. As a result, I'd see the process pop up in Task Manager, sit there a bit, then peace out.