We are having an issue on one of our clients relatively new sbs installs.

The domain consists of a single SBS 2011 server with 4 windows 7 clients and 3 xp clients. Most of the time everything is fine however roughly every 3 days windows 7 clients start timing out when trying to receive computer group policy.

This results in hour long delays before getting to the login screen in the morning. This is accompanied by event ID 6006, win login errors stating it took 3599 seconds to process policy. Once they've booted they can log in without issue however gpupdate fails again on computer policy and gpresult comes back with access denied, even when run as domain admin... At this point if we restart the server the network is fine for 3 days.

I thought perhaps it might be ipv6 or smb2, but disabling ipv6 on the clients doesn't help and the clients can browse the sysvol folder freely on smb2 anyway. Does anyone have any ideas or routes I can take to further diagnose the issue?

Thanks in advance :)