problem using out of the box SFTP client from UNIX

Facing problems executing certain commands using out of the box SFTP
client from UNIX while I have the J2SSH server on windows XP. Anybody
facing this problem.. I am using VirtualFileSystem and had to modify
that code to get this fixed.. Not sure if I am doing the right thing
though.. Basically it has something to do with the "drive:" format used
for file names on windows systems..
 
Thanks,
Gandhi