Step-by-step instructions:

1. Open the Command Prompt. Start > Run > cmd
2. Run the command: attrib -r -s -h "%SystemDrive%\boot.ini"
3. Open the file %SystemDrive%\boot.ini in Notepad.
4. Find your OS's boot line.
-- Here's what mine looks like.


Code:
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect


5. Try adding the following switches (if not already there):

/FASTDETECT - Specifying FASTDETECT causes NTDETECT to skip parallel and serial device enumeration for a boot into Win2K, whereas omitting the switch has NTDETECT perform enumeration for a boot into NT 4.0. Win2K setup automatically recognizes dual-boot configurations and sets this switch for BOOT.INI lines that specify a Win2K boot. Windows 2000/XP Only.

/NOGUIBOOT - When this option is specified the VGA video driver responsible for presenting bit mapped graphics during Win2K's boot process is not initialized. The driver is used to display boot progress information, as well as to print the Blue Screen crash screen, so disabling it will disable Win2K's ability to do those things as well. Windows 2000/XP only.

/NOSERIALMICE=[COMx | COMx,y,z...] - Disables serial mouse detection of the specified COM port(s). Use this switch if you have a component other than a mouse attached to a serial port during the startup sequence. If you use /NOSERIALMICE without specifying a COM port, serial mouse detection is disabled on all COM ports.