XnView Software

When I run a slideshow with use-keyboard-press and full-screen and loop options I should be able to get out of the show with Esc.
Sometimes (not always) that doesn't work. Then sometimes pressing Esc 5 or 6 times does the trick. But sometimes it has to be 50 or 60 times, and I'm afraid that one day . . .
Any explanation for this phenomenon?

Which OS?

Sorry for delay in answering, subscribe feature didn't work.
And now I regret I can't remember which of my two computers it happens on: either Windows Vista Home Premium or Windows 7.
Sorry about that; the problem is sporadic, so not easily reproduced.
Bart