I found this in a few different places around the 'net - hopefully it's helpful:
Correcting System Hang at Startup
If your system hangs about 2 or 3 minutes at startup, where you can't access the Start button or the Taskbar, it may be due to one specific service (Background Intelligent Transfer) running in the background. Microsoft put out a patch for this but it didn't work for me. Here's what you do:
- Click on Start/Run, type 'msconfig', then click 'OK'.
- Go to the 'Services' tab, find the 'Background Intelligent Transfer' service.
- Disable it, apply the changes & reboot.