mmtimer resolution question

[Robert Reif]

I'm trying to track down a problem with the direct sound
regression tests when run in emulation mode using the
wave api.  I'm getting a lot of FIXMEs and poor quality
playback.  The dsound mixer callback routine expects to
be called every 10 ms but is being called twice every 20
ms.  Setting the timer resolution to 1 ms didn't help.
I hacked the mmtimer to run at the requested 10 ms
interval and the playback problems disappeared.

Since the mmtimer thread uses WaitForSingleObject(sleep_time)
for it's timer source, has something changed recently which
would explain this behavior?