Q. I have Access Denied errors on my workgroup-joined SharePoint server. What might be the problem?

A. There is a setting, ForceGuest, which is normally enabled for workgroup-joined machines, that force authentication requests to always use the Guest account. If you want to use another account then you need to change the value HKLM\SYSTEM\CurrentControlSet\Control\Lsa\forceguest to 0 (which by default is 1). This will stop authentication requests on a workgroup machine from using the Guest account