Too long to shut down

I have a Dell Latitude C610 with 256M ram running W2kPro SP3. The shutdown procedure takes at least 45 seconds to get to the point where it actually shows progress. The error message in the application event log says “Windows cannot unload your registry class file. If you have a roaming profile, your settings are not replicated. Contact your administrator.” The error is generated by userenv. Everything I’ve read said that running SP3 would cure it . . . it hasn’t.