I had this issue I flxed it by:
-Disabling GLSL shading
-Going to fullscreen
-Putting UFO: AI in XP (SP2) compatibility mode.
-I'd suggest running as administrator (I didn't have to do this as I have UAC turned off and this is a administrator account so it defaults to administrator rights)
Things to note after doing the above:
-Do not change from windowed to fullscreen or fullscreen to windowed (battlescape will crash if you transition to or from it or do this while in it.)
-Do not re-enable GLSL (EVER!)
-Do not change gamma level while in combat it will crash (Do it before or after combat)
Which revision do you play?
I dont think that glsl shaders are in context with a crash to desktop from end turn button... if that game got a problem with glsl shaders it wouldnt not even load to battlescape or i would have graphic issues, same with the other problems that you talking about there is no relations with this bug.
we are talking special about END TURN/ FINISH ROUND button, i just want to be sure there is no mistake.