Windows client can’t access share

We are running a Windows 2008 AD with all clients being Windows XP.
Our file server is Apple Snow Leopard.
I have bound the file server to the AD.
The AD users have been applied appropriately on the Share.

So far so good.

However, Windows clients can’t access the file server…..not even the AD administrator account.

When trying to connect, the login windows comes after a looooooong time and even though I enter correct credentials it won’t allow a connection. I tried mapping and the same thing happens……login comes about after 5 minutes.

Servers can be pinged both directions.

Someone please help me. It’s quite urgent. Thank you!