If GPO Studio Crashes at startup due to invalid sample rate, it is possible
that your system is in a locked state, This is a known bug in GPO Studio 1.2, and it only occurs when GPO Studio is closed after a driver reported "invalid sample rate" and was left that way. (if you choose another driver which works before closing this bug doesnt occur)
so the only solution is to delete the
HKEY_CURRENT_USER\Software\Garritan Personal Orchestra Studio\device
key and restart the application.