User name and password needed when starting parallels

Every time i start parallels in have to type in my admin user name and password, I'm using parallels 3 with latest updates, and the windows vista I'm using is from my boot-camp partition. Everything seemed fine when i was using Xp but now I've upgraded to vista i need admin user name and password then it comes up initialising parallels tools, then all starts as normal till i need to shutdown, then i need to type in user name and password again, but only once this time, is there anything i can do to stop this happening.