3550: session setup failed: ERRDOS

Hi,
we have re installes our Windows domain and Activedirectory, and from then until now we can not mount shared windows filesystems on Linux server and we receive :

mount -t smbfs -o username=user1,password=xxxxx //xxx.16.0.xxx/dir
/mnt/dir

3550: session setup failed: ERRDOS - ERRnoaccess (Access denied.)
SMB connection failed

Any idea ?
Thank you.