This happened a couple of times on my W2k office workstation during normal audio playback. (plain MC, no extra plug-ins or skins).
Today I uninstalled MC, removed all MC related JRiver entries from the registry and reinstalled. After that I have worked several hours with other applications and played music with MC in the background. MC has worked fine so far.
The error has not happened on my XP HTPC, which has tons of multimedia stuff installed.
I wonder if MC's debug log could tell something. I'll enable it now and post the last lines if the problem comes back.
Media Center Registered 11.0.290 -- C:\Soft\MC\
Microsoft Windows 2000 5.0 Service Pack 3 (Build 2195)
AMD Athlon 1396 MHz MMX / Memory: Total - 1048 MB, Free - 796 MB
Internet Explorer: 6.0.2800.1106 / ComCtl32.dll: 5.81 / Shlwapi.dll: 6.00.2800.1400 / Shell32.dll: 5.00.3502.6144 / wnaspi32.dll: 4.71 (0002) , ASPI for Win32 (95/NT) DLL, Copyright © 1989-2002 Adaptec, Inc. / Aspi32.sys: 4.71 (0002)
Ripping / Drive G: Mode:ModeSecure Type:Auto Speed:Max
Digital playback: Yes / Use YADB: Yes / Get cover art: Yes / Calc replay gain: Yes / Copy volume: 32767
Eject after ripping: Yes / Play sound after ripping: No
Burning / Drive G: PHILIPS CDRWDVD2010 Addr: 1:0:0 Speed:20 MaxSpeed:20 BurnProof:Yes
Test mode: No / Eject after writing: Yes / Direct decoding: Yes / Write CD-Text: Yes
Use playback settings: No / Normalization: None