Troubleshoot Your Boot-Up and Shutdown Problems
Why does my PC occasionally freeze at Windows' boot-up screen?
brn2rnjk1, Answer Line forum
First, you need to figure out if this a Windows problem or a hardware problem. Try to notice at what point the computer hangs (admittedly difficult if the problem doesn't happen regularly). If Windows starts loading before disaster strikes, that means there's an issue
If you're unsure where the problem is, try to isolate it by booting from a CD, DVD, or flash drive. Again, the intermittent nature of your problem makes the task
Of course, the culprit could be a boot device other than the hard drive. If your PC tries to boot from the CD/DVD drive before the hard drive (as most do), a defect in that drive may interfere with the boot even when the drive is empty. This could also be the case with USB ports and floppy drives.
To determine which drive could be the cause, go into your system setup program and change the boot order. I can't tell you how to do this exactly, since it varies from BIOS to BIOS; look for a message soon after the PC boots that says something like 'Press F2 for Setup'. Once in the setup program, search the menus for something like 'Boot Options' or 'Boot Order'. Make your hard drive the first device in the boot order, and then save and exit. If that fixes the problem, experiment with putting different devices before the hard drive, one at a time, until the problem returns. Then you'll know the culprit.
In Video: How to Start Up Your PC Faster
If all of the above tests point to a hard-drive problem, Answer Line forum member
If that doesn't help, and the PC freezes before the Windows logo appears, open the computer's case (if it's a desktop) and check the cables connecting the hard drive to the motherboard and the power supply. You might even consider replacing them. If you have a laptop, bring it to a shop and have a professional look at it.
If Windows comes up and then freezes, something is wrong with your boot or autoloading sequence. The Event Viewer may tell you what. Select Start, Run, type eventvwr, and press Enter. In the left pane, select System. In the right (XP) or center (Vista) pane, find and double-click an event with a red flag and the word Error. If the resulting dialog box doesn't provide useful information, click the URL in the description box (XP) or click the Event Log Online Help link (Vista).
Finally, you might try fiddling with your autoloading programs. Windows launches them all at once, and that can cause conflicts. Use R2 Studios' free Startup Delayer to insert delays before some of your autoloading programs. You might also consider disabling some autoloaders. See "Why Is My PC Acting Up?" for details.
For background, see the original forum discussion.