Mp3 bitrate showing 0 kbps

[yash.yash]

I have Windows XP Professional x64 with Service Pack 2 installed along with Windows Media Player 11 x64. The problem is that in windows explorer, the bitrate field of all mp3 is showing 0 kbps. But when I check out the bitrate by playing the mp3, wma displays it correctly eg - 256 kbps or 320 kbps etc.

I am utterly confused as to how can I solve this problem? I did not face these problems when I had both xp and wma x86 (32-bit)

[VexByte]

MP3's which were encoded using VBR mode shows 0 kbps and the encoding was not perfect.

How is the music quality ?