If for some reason, you need to only temporarily disable startup programs from starting up during boot time, you can do so easily. This worked in Windows XP – but does not work in later versions.
Temporarily disable Startup applications in Windows
Simply hold down the Shift key during the logon process. This will prevent Windows from starting up the programs or shortcuts located in the following folders:
C\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup C\Users\username\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup
To disable the programs or shortcuts you must hold down the SHIFT key until the desktop icons appear. Holding down the SHIFT key is a better alternative than temporarily deleting or moving programs and shortcuts because this procedure affects only the current user session.
To use the SHIFT key to disable programs and shortcuts in startup folders, log off the computer. Now in the Welcome to Windows dialog box, press Ctrl+Alt+Del.
In the Log On to Windows dialog box, type your user name and password and then click OK. Immediately hold down the SHIFT key. The mouse cursor changes shape from a plain pointer to a pointer with an hourglass. Continue to hold down the SHIFT key until the Windows desktop icons appear and the mouse cursor stops changing shape.
This is especially useful if you need to troubleshoot Windows start-up issues or logon delays.