samba - Jun 2014 - File copy results in 100% CPU load and broken connection

Good day.

There  are Samba server, When Windows 7 client copying files from those
server  share,  smbd  process,  serving  this  connection, load his CPU
kernel  up  to  100%  permanently.  Some  times (not always) file copy progress
on
windows  client  stops  with message that share not available . After that
windows reconnects
with  new  connection (new smbd process on samba server), but previous
smbd continuous 100% loads CPU kernel. Is this situation normal?

Additional information:
Samba server:
      Debian 7.5 x64
      Kernel version 3.2.0-4-amd64 #1 SMP Debian 3.2.57-3+deb7u2 x86_64
GNU/Linux
      Samba version (debian package) 3.6.6-6+deb7u3
      smb.conf:
      [global]
        dos charset = CP866
        workgroup = TRAZT
        server string = %h server
        interfaces = lo, bond0
        bind interfaces only = Yes
        client schannel = Yes
        server schannel = Yes
        allow trusted domains = No
        passwd chat         restrict anonymous = 1
        syslog = -1
        log file = /var/log/samba/log.%m
        max protocol = SMB2
        reset on zero vc = Yes
        max xmit = 65536
        name resolve order = wins lmhosts host bcast
        time server = Yes
        unix extensions = No
        deadtime = 15
        load printers = No
        show add printer wizard = No
        logon script = scripts\%U.bat
        logon path         logon drive = U:
        logon home = \\%L\%U
        domain logons = Yes
        os level = 65
        lm announce = No
        preferred master = Yes
        domain master = Yes
        dns proxy = No
        wins support = Yes
        async smb echo handler = Yes
        multicast dns register = No
        idmap config * : backend = tdb
        invalid users = root
        force unknown acl user = Yes
        hosts allow = 127.0.0.1, 192.168.1.0/24
        hosts deny = 0.0.0.0/0
        aio read size = 16384
        aio write size = 16384
        strict allocate = Yes
        use sendfile = Yes
        hide special files = Yes
        map archive = No
        browseable = No
        access based share enum = Yes
        csc policy = disable
        follow symlinks = No
        dont descend = /proc,/dev
        log level = 1

[homes]
        comment = Home Directories
        valid users = %S
        read only = No
        create mask = 0600
        directory mask = 0700

[netlogon]
        comment = Network Logon Service
        path = /var/lib/samba/netlogon
        write list = "+TRAZT\Domain Admins"
        guest ok = Yes

[AztZik]
        path = /mnt/work/aztzik
        valid users = +aztzikusers
        force group = aztzikusers
        read only = No
        create mask = 0660
        directory mask = 0770


Windows  client:  Windows 7 x64 Professional SP1 + all actual windows updates