As per this thread - same problem:
This started to happen to me on Creo4 M040, when I added the trail file to the startup command.
It looks like Creo is not able to proceed with the trail file, when it encounters license message and it is not able to activate the license message dialog properly at the same time, because it wants to finish the startup trail file first.
As I need my startup trail file anyway, I have not found any workaround for this behavior and killing the Creo in Windows Task Manager is the only solution left.
