|have you tried using msconfig and disabling all startup devices to see if you still have the problem.|
What happens is that people who are not PC savvy don't realize that by installing printers and programs on a PC have all of that stuff going into start-up which is not needed. So the more you install, the more the startup jams up.
The only thing you really need running is your AV and the task scheduler.
Any questions, here is a simple How-To to help you on this matter:
I actually use that daily when I'm doing my PC repairs ;-)
Some HELP in posting on Computing.net plus free progs and instructions Cheers