Ok, I had some time to test the iGuidance versions earlier, and here are the results.
First off, I must exclaim:

!!!!
I uninstalled 2.0.2 and reverted back to 2.0: iGLauncher worked properly once, and then stopped clicking OK and embedding like it should. Then I changed the timing, and it worked properly once more. NoNag didn't work at all.
Then, for kicks, I reinstalled 2.0.2 and tried it again. Same behavior for iGLauncher 1st time, then it quit working altogether, regardless of timing. Same behavior again for NoNag - no go.
Uninstalled 2.0.2 and reinstalled 2.0 again, and it hasn't worked since.
Since iGLauncher did work the one time in 2.0.2, and the rest of the behavior was the same for iGLauncher and NoNag, regardless of version, I'm going to presume that my previous guess that it was the iGuidance version is incorrect, and that it is in fact something going on with my desktop PC.
Just as an FYI, I left NoNag running as a TSR with the /stayresident switch, and killed the process before each test.
If you have any suggestions, or anything you want me to try - short of a fresh Windoze installation - let me know.
If it's working properly for everyone else, ignore me for now - I still have an "older" iGLauncher running smoothly in the car, where it matters