Thank you for your response Martin.
we have 5 DCs, 1 for each subnet. On my own PC where the GPO is not working, I ran "gpupdate" with this result:
Updating Policy...
User policy could not be updated successfully. The following errors were encount
ered:
The processing of Group Policy failed. Windows attempted to read the file \\DomainName\SysVol\DomainName\Policies\{09BC1802-E96D-43CB-8EE1
-90CF9C8C9C7B}\gpt.ini from a domain controller and was not successful. Group Po
licy settings may not be applied until this event is resolved. This issue may be
transient and could be caused by one or more of the following:
a) Name Resolution/Network Connectivity to the current domain controller.
b) File Replication Service Latency (a file created on another domain controller
has not replicated to the current domain controller).
c) The Distributed File System (DFS) client has been disabled.
Computer policy could not be updated successfully. The following errors were enc
ountered:
The processing of Group Policy failed. Windows attempted to read the file \\DomainName\SysVol\DomainName\Policies\{09BC1802-E96D-43CB-8EE1
-90CF9C8C9C7B}\gpt.ini from a domain controller and was not successful. Group Po
licy settings may not be applied until this event is resolved. This issue may be
transient and could be caused by one or more of the following:
a) Name Resolution/Network Connectivity to the current domain controller.
b) File Replication Service Latency (a file created on another domain controller
has not replicated to the current domain controller).
c) The Distributed File System (DFS) client has been disabled.
To diagnose the failure, review the event log or run GPRESULT /H GPReport.html f
rom the command line to access information about Group Policy results.