That sounds like a non-standard format. Can you play the files with any other player?
Yes: realOne, Windows Media Player, Nero Media, Nero Wave editor, Foobar2000, Unrealplayer (UIQ).
For what it's worth, my system information:
Media Center Registered 10.0.43 -- C:\Programme\Media\J River\Media Center\
Microsoft Windows XP 5.1 Service Pack 1 (Build 2600)
Intel Pentium 4 1773 MHz MMX / Memory: Total - 1047 MB, Free - 639 MB
Internet Explorer: 6.0.2800.1106 / ComCtl32.dll: 5.82 (xpsp1.020828-1920) / Shlwapi.dll: 6.00.2800.1276 / Shell32.dll: 6.00.2800.1233 (xpsp2.030604-1804) / wnaspi32.dll: 4.60 (1021) , ASPI for Win32 (95/NT) DLL, Copyright © 1989-1999 Adaptec, Inc. / Aspi32.sys: 4.60 (1021)
Ripping / Drive D: Copy mode:Normal CD Type:Auto Read speed:Max
Drive E: Copy mode:Normal CD Type:Auto Read speed:Max
Digital playback: Yes / Use YADB: Yes / Get cover art: No / Calc replay gain: Yes / Copy volume: 32767
Eject after ripping: No / Play sound after ripping: No
Burning / Drive D: PHILIPS DVD+RW-D01 Addr: 1:0:0 Speed:12 MaxSpeed:12 BurnProof:No
Test mode: No / Eject after writing: Yes / Direct decoding: No / Write CD-Text: No
Use playback settings: No / Normalization: None