PlaySoundTest.test_alias_fallback(): Disabled this test, and explained

why in a new comment.  My home Win98SE box is one of the "real systems"
alluded to (my system "default sound" appears to have vanished sometime
in the last month, that's certainly not a Python bug, and the MS
PlaySound docs are correct in their explanation of what happens then).

Bugfix candidate.  If someone can still sneak it into 2.3.1, that would
be good.

Lib/test/test_winsound.py

@@ -71,7 +71,18 @@ class PlaySoundTest(unittest.TestCase):
         winsound.PlaySound('SystemQuestion', winsound.SND_ALIAS)
 
     def test_alias_fallback(self):
-        winsound.PlaySound('!"$%&/(#+*', winsound.SND_ALIAS)
+        # This test can't be expected to work on all systems.  The MS
+        # PlaySound() docs say:
+        #
+        #     If it cannot find the specified sound, PlaySound uses the
+        #     default system event sound entry instead.  If the function
+        #     can find neither the system default entry nor the default
+        #     sound, it makes no sound and returns FALSE.
+        #
+        # It's known to return FALSE on some real systems.
+
+        # winsound.PlaySound('!"$%&/(#+*', winsound.SND_ALIAS)
+        return
 
     def test_alias_nofallback(self):
         try: