How to create a daily task that repeats every 15 mins EXCEPT between the hours of 12AM – 2AM

You could run it silently using a Windows Script file instead. The Run Method allows you running a script in invisible mode. Create a .vbs file like this one

Dim WinScriptHost
Set WinScriptHost = CreateObject("WScript.Shell")
WinScriptHost.Run Chr(34) & "C:\Scheduled Jobs\mybat.bat" & Chr(34), 0
Set WinScriptHost = Nothing

and schedule it. The second argument in this example sets the window style. 0 means "hide the window."

Complete syntax of the Run method:

 object.Run(strCommand, [intWindowStyle], [bWaitOnReturn])

Arguments:

• object: WshShell object.
• strCommand: String value indicating the command line you want to run. You must include any parameters you want to pass to the executable file.
• intWindowStyle: Optional. Integer value indicating the appearance of the program's window. Note that not all programs make use of this information.
• bWaitOnReturn: Optional. Boolean value indicating whether the script should wait for the program to finish executing before continuing to the next statement in your script. If set to true, script execution halts until the program finishes, and Run returns any error code returned by the program. If set to false (the default), the Run method returns immediately after starting the program, automatically returning 0 (not to be interpreted as an error code).

Assuming you're just setting the task to "Repeat" in the XP "Scheduled Tasks" system, no further action on your part is needed. Scheduled Tasks won't "Repeat" a task if it's already running.

If you want to override that default, you can check the box "If the task is still running, stop it at this time" to cause the task scheduler to kill the last instance before starting a new one (though it sounds like you probably don't want that).