Lion Server AD authentication

I have a annoying problem; OSX Lion Server 10.7.5 binded to AD (2008 server)

There is emc storage attached to the mac server, i created a couple of shares for it.

I gave Active Directory groups acces rights on the shares that I created on the Lion Server.

I have 60 mac clients which are all working fine connect on their mac to the shares on the Lion server with their AD accounts.

So far so good, now there are a couple of Win7 users who need to access the shares as well.

Initially I cannot connect from a Win7 machine to the share on the Lion Server.

But when i (once) make the connection on a mac with the account of the user, then go back to the Win7 machine i CAN make the connection. this works until i reboot the server, then the connection is lost and it will not be possible to connect again until i authenticate via a mac client to the share..

Anyone an idea?

Looks like it caches the credentials somewhere and after a reboot the cache is empty.. So the direct route from Win7 via OSX Lion server to the AD is somewhere crappy..

Edwin