So I double click the FileMaker icon on my desk top. Nothing happens. I right click it and choose "open". Nothing happens.
So I decide to close all apps and reboot. But just before I reboot, I decide to launch TaskManager. (Using Windows 7.) Lo and behold, there's the FileMaker.exe file open and running.... So I use task manager to force quit it. I wasn't concerned about damaging a file as I didn't have any files open. Then I tried to launch FileMaker and it opens as expected.
Mulling this over, I recalled that FileMaker acted a bit strangely last night. I closed all regular FileMaker files and ended up with an empty desktop except that the data viewer window was still open. So I closed the data viewer and all seemed closed. But now that I thought about it, I should have seen the launcher window and didn't. I also recalled that after testing and adjusting some scripts in the Adventures In Filemaking #2 file to use a card window to display the splash logo, some system dialogs started persistently opening in the far top left corner of my 1st monitor--the 0,0 position in terms of distance from top and left.
So my hypothesis is that the launcher window managed to open "off screen" where I couldn't see it. This is purely hypothesis as I didn't have a way to confirm this, but as a precaution, I then went into preferences and reset the defaults for window sizes and positions.
I'm sharing this as this might help out some other developers. If you can't get the app to launch, use TaskManager to check and see if it may be launched but invisible.