I've been having problems with my HP laptop for the past month. When ever I boot up, it will stay on the logo screen for a long time, then it will go to the part where it boots up vista with the loading bar and it will usually freeze and look dark on the loading bar (as in it looks transparent). It's not a virus or spyware, malware, etc, I have run numerous scans to no avail.
One way of solving this is to use the msconfig config utility to disable startup items and services. Then iof the problem goes away, slowly add back in startup processes and services till you find what is causing the problems.
To run msconfig just type in the start menu's search bar msconfig and click on what comes up.
It won't work. When I get to the vista logo, it loads really fast and it's not slow. But when I'm at the POST screen and the loading bar, sometimes it takes a long time or the loading bar freezes before it fully comes up.