Check the install guide for information about authorization required on the id used to install DB2. Under Windows, it is much trickier than under Linux, UNIX becasue DB2 wants the user to have administrator authority. I am not sure which version you are using, but at one time if your userid was part of a domain, it had to be the domain administrator.
However, you may be able to go into Window Services and specify which userid you want DB2 to logon with to resolve the problem.