In vista it is possible to locate the service file location from taskmanager.
1) Try to find it from which location it is running. Few viruses are capable of creating a startup entries, but after they create, the virus might get deleted by your antivirus program. In such case it will show thw errors from left out entries.
If you didnt find the process from task manager follow this step
2) Go to run command and type "msconfig"(without quotes) in that windows find startup tab and find the service which is giving error. you can remove that process from startup.
Let me if it solve you problem.