LinuxQuestions.org - problems with mounting a windows 7 shared folder in linux

Ok here is the situation, i have a mixed network(windows xp, windows 7, some linux machine (centOS)), the linux machine works as a server, and i want the server to have access to the shared folders of the other machines connected in the local network.
i have no problem mounting shares from windows xp, i have problems with the windows 7 shares.

Code:

smbtree

returns

Code:

WORKGROUP

#some othe shares

 \\MACHINENAME

cli_rpc_pipe_open: cli_nt_create failed on pipe \srvsvc to machine MACHINENAME.  Error was NT_STATUS_ACCESS_DENIED

tried with

Code:

smbtree -U username

same result.
Then i tried

Code:

nmblookup MACHINENAME

the result

Code:

192.168.1.5 MACHINENAME<00>

169.254.249.23 MACHINENAME<00>

where can 169.254.249.23 come from?
the i tried to mount directly with the IP

Code:

mount -t cifs //192.168.1.5/sharename /mnt/aa/ -o user=username

the result

Code:

mount error 5 = Input/output error

Refer to the mount.cifs(8) manual page (e.g.man mount.cifs)

the windows 7 user has only username, with no password. any idea where the problem may come from?
not quite sure is this is a linux problem, but it would be nice to have some light on the issue, where might the problem be coming from.