I've got a similar issue after upgrading.
The Win7 GPO Log shows:
Found file system path of: <\\llama.lan\sysvol\llama.lan\Policies\{31B2F340-016D-11D2-945F-00C04FB984F9}>
NetDfsGetClientInfo() failed with error=0xa66 for GPT Path=\\llama.lan\sysvol\llama.lan\Policies\{31B2F340-016D-11D2-945F-00C04FB984F9}\gpt.ini
Couldn't find the group policy template file <\\llama.lan\sysvol\llama.lan\Policies\{31B2F340-016D-11D2-945F-00C04FB984F9}\gpt.ini>, error = 0x2. DC: <null>
No errors listed with samba-tool dbcheck, but do get the same samba.provision.ProvisioningError with samba-tool ntacl sysvolcheck
The sysvol share is listed when accessed via explorer: \\llama.lan - but the share is not accessible.
It can be accessed by using the name of the domain controller/Zentyal server 'dc01':
\\dc01.llama.lan\sysvol works
So does \\dc01\sysvol
This may be what's causing slow logins on my Windows 7 machine (2-5 minutes) while waiting for the Machine policies to be applied.
If I reboot the windows machine and leave it for 10 minutes then login only takes a couple of seconds.
I've tried all the suggested solutions for this issue - but it looks like it might be a permission/configuration problem.