Data Directory Empty but Server run again

Hi,Incredible.

When i look with windows explorer my server data directory, i saw an empty data directory !!

But users can used server again.

If i execute, under Windows, Run… and type e:\lotus\domino\data\mail, i can see all mailfile. If i do same thing with data directory (e:\lotus\domino\data), the directory is empty.

If i look properties of data directory, windows says size : 0 bytes, 0 files, 0 folders !!! But Domino Server run again.

Anyone can help me please.

Thanks a lot.