samba - Aug 2009 - Win clients connection drops while copying large files, errors in logs

I have a problem with samba (3.2.3) not working properly with windows  
clients.
I run a FC11 samba storage server, that has windows and mac client  
machines connecting to it. So far mac clients work. However windows  
client, whenever I try to install some application that is stored on  
the samba server, or even copy a very large file (few gbs) I get this  
in /var/log/messages and the file transfer or the install interrupts :

Errors:

Aug 16 02:05:10 localhost smbd[7153]: [2009/08/16 02:05:10, 0] lib/ 
util_sock.c:read_socket_with_timeout(939)
Aug 16 02:05:10 localhost smbd[7153]: [2009/08/16 02:05:10, 0] lib/ 
util_sock.c:get_peer_addr_internal(1676)
Aug 16 02:05:10 localhost smbd[7153]: getpeername failed. Error was  
Transport endpoint is not connected
Aug 16 02:05:10 localhost smbd[7153]: read_socket_with_timeout: client  
0.0.0.0 read error = Connection timed out.
Aug 16 02:05:10 localhost smbd[7153]: [2009/08/16 02:05:10, 0] lib/ 
util_sock.c:write_data(1136)
Aug 16 02:05:10 localhost smbd[7153]: [2009/08/16 02:05:10, 0] lib/ 
util_sock.c:get_peer_addr_internal(1676)
Aug 16 02:05:10 localhost smbd[7153]: getpeername failed. Error was  
Transport endpoint is not connected
Aug 16 02:05:10 localhost smbd[7153]: write_data: write failure in  
writing to client 0.0.0.0. Error Broken pipe
Aug 16 02:05:10 localhost smbd[7153]: [2009/08/16 02:05:10, 0] smbd/ 
process.c:srv_send_smb(74)
Aug 16 02:05:10 localhost smbd[7153]: Error writing 75 bytes to  
client. -1. (Transport endpoint is not connected)


My smb.conf:

[global]
workgroup = workgroup
server string = Server %v
netbios name = Server
hosts allow = 10.0.1.0/24
;interfaces = lo eth0 192.168.12.2/24 192.168.13.2/24
log file = /var/log/samba/log
log level = 3
max log size = 50
#security = user
passdb backend = tdbsam
printcap name = /etc/printcap
#smb ports = 445 <<<< tried to have it run only on 445, read
somewhere
it might help, but it didnt.

[homes]
comment = Home Directories
browseable = no
writable = yes
;	valid users = %S
;	valid users = MYDOMAIN\%S
valid users = skfx	

[media]
comment = Media Storage
path = /media
writable = yes
valid users = skfx
guest ok = no
browseable = yes

Happens on all windows machines and Im fresh out of ideas, please help.