A W2K3 terminal server (and domain controller) failed to apply my group policies when users logged into their RDP sessions recently. Today I set about to fix this. Checked the application event log and found that event 1054 had been logged every 5 minutes for the last five months (almost since the server was installed!). Filtering the log for event 6009 showed that the server had been restarted a handful of times during that period. Running gpresult in a user's RDP session returned an error “The user does not have RSoP data”. I checked DNS, restarted the netlogon service, ran ipconfig /registerdns, and checked file system permissions.
Eventually, I found a site that noted a correlation between group policy errors and AMD's multi-core CPUs. The server has an AMD processor, so I pinged the localhost and got some wild numbers in response. Installing a patch from AMD (their "Dual-Core Optimizer") resolved the incorrect ping times, the application log errors, and my issues with group policy!