Can't write to a disk share

[Michel Kenny]

    Hi there. I'm running Samba 2.2.2 on a Red Hat 7.2 system. I've set up a
few disk shares (with the writable option set to yes), but I can't write to
them. I can read from them ok, so I don't know what the problem is. I'm
trying to write to the shares from a Windows 2000 Professional computer.
Here's a part of my logs that appear every time I try to write to a share:

[2001/12/02 20:22:17, 1] smbd/service.c:make_connection(610)
  michel (192.168.101.4) connect to service website as user michel (uid=500,
gid=500) (pid 5160)
[2001/12/02 20:22:18, 0] smbd/password.c:authorise_login(906)
  authorise_login: rejected invalid user nobody
[2001/12/02 20:22:18, 0] smbd/password.c:authorise_login(906)
  authorise_login: rejected invalid user nobody
[2001/12/02 20:22:19, 0] smbd/password.c:authorise_login(906)
  authorise_login: rejected invalid user nobody
[2001/12/02 20:22:19, 0] smbd/password.c:authorise_login(906)
  authorise_login: rejected invalid user nobody
[2001/12/02 20:22:19, 0] smbd/password.c:authorise_login(906)
  authorise_login: rejected invalid user nobody

Any help would be greatly appreciated.

Michel Kenny