Dell Laptop M1730, OS Vista Ultimate.
OS Loads fully at start up all programs also load, but laptop then freezes for 30 seconds, then alls fine.
Have tried registry booster, and antivirus/malware scans all clear.
CPU hits 50/70 at this point, then alls ok.
You might want to run "msconfig" in the run box. Then run in diagnosis mode. Reboot and see if it hangs.
If it doesn't, then run msconfig again, put it back to your normal startup, and disable the item in the startup tab.
Reboot, and if its good, the start enabling things in the startup tab, couple at a time and rebooting, till you get a hang.
It sounds like somethings not running right, and may need to be reinstalled/fixed.