problem with booting

I am using beagle board which i boot from sd/mmc card with kernel
image and file system.MMC card is made bootable correctly.

I had already boot beagle board,mounted the file system and worked
with it,It was working properly.

But suddenly due to some unknown reasons, Now as I setup the hardware
and try to boot the beagle board it shows following statements and
repeatedly shows it.Looks like u-boot is not booting properly.

Texas Instruments X-Loader 1.5.0
Beagle xm

This two statements are repeatedly shown by the beagle board,it
doesn't boot...please help me out...