which USB Drive is causing the problem by changing the boot

There could be a variety of other problems which could affect your computer.If you give the shut down command and your computer restarts instead, it means there is something causing a system failure during the shutdown process. To stop this, you will have to click on the 'Start' button and click on 'Run'. In 'Run", type 'sysdm.cpl' and hit 'Enter'. In the window that appears, you will have to click on the Advanced Tab Settings Start up and Recovery. Go to the 'Automatically Restart' option and uncheck the box next to it. You will notice that your windows has stopped rebooting but the system failure problem still persists. However, the error message windows will display when your computer starts, will give you the cause of the problem. At times, this problem could also be due to a hardware error. It is therefore advisable to call a qualified computer repair personnel to solve this problem.If your computer screen freezes before windows is loaded from the hard drive, there is a hardware problem. To figure this out, try booting your computer from a USB Flash Drive or a CD/DVD. If your computer boots from any other drive apart from the hard drive, a fault in that particular drive could interfere with the booting even after you have emptied the drive.
You will have to figure out which USB Drive is causing the problem by changing the boot order from your BIOS settings. When your computer starts, you might get a message saying 'Press F2 for Setup' and look for 'Boot Order' or 'Boot Options'. In the boot order, keep your first option as "Hard Drive', and exit. If this stops your problem, you can try putting different devices in the first option and figure out which drive is faulty.Windows is programmed to ask for a password before starting, only to protect your computer from somebody else using it, without your consent. But if you have trustworthy people around, and don't mind them using your desktop computer, you can easily remove this option. To turn off the password characteristic, you should first click on the 'Start' button and then on 'Run'. In 'Run' type the command - 'controluserpasswords2', and hit 'Enter'. In the window which appears, you will find an option 'users must enter a username and password to use this computer. Uncheck the box next to this and click 'OK'. Once you do this, a dialog box will appear on screen, wherein you need to type your username and password for the last time. Post this, your computer will boot automatically without asking you for any password.
Troubleshooting certain computer startup problems may require help from qualified technicians. This is when problems are due to certain technical issues which are beyond comprehension of common people lacking specific knowledge. Regularly updating and maintain your computer is enough to keep most problems at bay. The biggest change for the better is the Auto ISO feature. Even in very dark conditions the USB Flash Disk is still able to acquire auto focus. A useful new feature in the Canon EOS 1D Mark IV is being able to register two different AF points based on camera orientation. Images taken with the Canon EOS 1D Mark IV are sharp and have good color even at high ISO settings, which make it a good choice for shooting in low light level conditions.The layout of the Canon EOS 1D Mark IV buttons is intuitive making adjustments easy even while looking through the viewfinder. The Canon EOS 1D Mark IV is solidly build and can withstand general bangs and knocks. A useful new feature in the Canon EOS 1D Mark IV is being able to register two different AF points based on camera orientation.