Windows Server 2008: Unable to edit group policies

I have a customer with a Windows Server 2008. I am needing to update their password policy but I cannot edit any of the group policies. If I try and edit the password policy I get the error

"The system cannot find the file specified. Failed to save \\domain\sysvol\domain\Policies\{GUID}\Machine\Microsoft\Windows NT\SecEdit\GptTmpl.inf. Make sure that this object exists."

If I try and add a mapped drive is give me an empty message prompt with error as the title.

I have checked the permissions on the sysvol and have disabled anti-virus but still get issues.