Have a 2GB Sansa Clip that is not showing all of the music that I have on the MP3 player. When I plug it up to a Windows 2000 machine, I see every song that I have placed on it every since I bought it. When I plug it up to a Windows XP machine, I only see the factory default music and folders that came with it. Also on the Windows XP machine, I see only recent songs that I placed on the mp3 player. Did do the firmware upgrade and still having the same problem. Tried sync with Windows Media Player and nothing seems to work.

The Clip connects to your computer in either of 2 USB connection modes, MSC or MTP.  You can set the mode.  When connected in MSC mode, your computer only sees files that had been transferred to the Clip while in MSC mode; same as to MTP mode.  The Clip also can be set to Auto mode, in which it tries to connect in MTP mode but then will fall back to MSC mode.

With your older system, you were connected in MSC mode, due to the older system’s software limitations; with your XP system, you connected up in MTP mode (and the original SanDisk songs were put on your player in MTP mode).

Easiest way to handle this issue:  just set your player to MSC mode, under Settings/USB.  The only limitation MSC mode has, in which your player is seen as a separate drive, is that MSC mode will not work for files using protection (DRM, digital rights management)–MTP mode is needed for that.

Hope this helps you out.