Unable to add default folder - Memory Card

Question

Hi,

I am using Samsung E250. I have one 1 GB Memory card attached to the cell. Today I copied around 50 Mp3 files and some picutres from my system to the phone memory card. Then I tried to open the folder[Memory Card] via phone, I am getting this error :"Unable to add default folder : Root directory full" ...

Please help me
Thanks,
Sridhar