Please click on Start and then to Run
Type in msconfig and press Enter
Now click on Services
Click on the Hide All Microsoft Services
Then uncheck everything and press Apply button.
Restart your system now
If system boots correctly and is running smoothly and faster then we have a startup problem
Try going back into msconfig and check one item and reboot
Keep doing that till you have found the problem or all are finally checked.
Post back with the results