WMP 9 & MPEG-->LPCM playback issue

Issue:
WMP v9.00.00.308 fails to render audio from MPEG2-->LPCM encoded files.
Same files consistently play properly using PowerDVD or ATI File Player v8.6
with inclusive Cyberlink DVD codec.

LPCM test file encoding formats:
48khz, 16 bit, LPCM encoded audio (15 seconds).
92khz, 24 bit, LPCM encoded audio (15 seconds).


Steps:
1. Logon to WinXP account (Admin rights), from fresh system start.
2. WMP-->File-->Open and select lpcm encoded mpeg2 test file.
3. Test file plays normally.
4. Close WMP.
5. Reopen WMP and attempt to play same or another lpcm formatted mpg file.
6. WMP renders video only, audio fails to render; no errors or other
feedback.

Close-all and logoff current account.
Logon to same account as above and steps 1-6 are repeated.

Summary:
Everything works correctly at first logon until wmp is closed. Once closed,
after first use, wmp will no longer render lpcm encoded audio until user
logoff/ on again. The problem is suggestive of a registry/ driver caching
issue, but I can no longer see the Forrest hidden so deep within all those
trees.

It's late, very late, and now I need sleep...

Ideas anyone?

--
Digger