disk getting hammered boot

What is with Vista B2 hammering the disk right after logon for 2-4 mins? I have a Dell XPS 600 3.0Ghz Dual Core Pent D 2 GIG RAM 60GIG 10K SATA drive on an nForce4 motherboard .... I mean, this is a rockin' computer and it's just getting hammered so much the first 2-4 mins I literally can't do anything because if I do I'm sitting here waiting anyways while the system catches up. I do notice that DWM.EXE is running and using some processor while it's happening?!??! anyone know what is causing this and if it's a bug or by design or what??? Thx! Billy