Two Things

Try "User Profile Hive Cleanup Service." You can get it at http://www.microsoft.com/downloads/details.aspx?familyid=1b286e6d-8912-4e18-b570-42470e2f3582&displaylang=en. I used to have a similar or the same problem, and this has helped tremendously.

Also, I recently removed Norton 360 from my machine and replaced it with Avast! and Online Armor (both free) and shutdown and startup times are now about 10 times faster.