/usr/bin/ls: .: Stale NFS file handle --> ???

I have put up a linux box as a router for a windows lan.

The person that asked me this wanted a fat32 partition on it for data., so
I have a 2Gb partition for linux, 128Mb partition for swap and a 30Gb
fat32 partition for data.

The 30Gb partition is also shared with samba. I can access this pc with
ssh and vnc.

The problem that I have is that there is a directory in the 30Gb partition
that I cannot read, but it works fine when accessed by amule (p2p program).

I don't have NFS (nfsd is loaded at sturtup, but I have not configured it).

When I try to do ls in that partition I get:

"/usr/bin/ls: .: Stale NFS file handle"

The fat32 partition is read/write, I mount it as user, and I get the same
error also if I try to read it as root.

Other dirs on that partitions work fine.

I have not find anything on google..
Please someone help me...

Thanks
Francesco