This is my system information:
Media Center Registered 10.0.91 -- C:\Program Files\J River\Media Center\
Microsoft Windows XP Workstation 5.1 Service Pack 1 (Build 2600)
Intel Pentium 4 3190 MHz MMX / Memory: Total - 1047 MB, Free - 617 MB
Internet Explorer: 6.0.2800.1106 / ComCtl32.dll: 5.82 (xpsp1.020828-1920) / Shlwapi.dll: 6.00.2800.1400 / Shell32.dll: 6.00.2800.1233 (xpsp2.030604-1804) / wnaspi32.dll: 4.71 (0001) , ASPI for Win32 (95/NT) DLL, Copyright © 1989-2002 Adaptec, Inc. / Aspi32.sys: 4.71 (0001)
Ripping / Drive E: Mode:Normal Type:Auto Speed:Max
Drive F: Mode:Normal Type:Auto 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: Yes Soundfile: chord.wav
Burning / Drive E: HL-DT-ST DVDRAM GSA-4040B Addr: 3:0:0 Speed:4 MaxSpeed:24 BurnProof:Yes
Drive F: LITE-ON LTR-48246S Addr: 3:1:0 Speed:48 MaxSpeed:48 BurnProof:Yes
Test mode: No / Eject after writing: Yes / Direct decoding: Yes / Write CD-Text: No
Use playback settings: No / Normalization: None
The missing drives (D & K) are NTFS as is Drive c:. They show us fine in Windows Explorer and other program applications.