samba - Sep 2004 - cp input/output error

Hi

I have been getting random input/oput error when trying to cp a ISO 
(100mb) to a samba mount point. I get the same random error when I try 
to cp a txt file over too.

cp: writing `/public/cd.iso': Input/output error

my fstab:
//fserv/public          /public smbfs fmask=666,username=,password= 1

Thanks,
Liming