G'morning Wyneth and welcome to the forums!

i have heard of this a couple of times. the command is set up properly as it runs wow.. BUT.. the wow window does not maximize. this implies another window is indeed in front of the wow window. (the first time i heard of this i immediately thought virus/trojan)

find wow.exe in your windows explorer... right-click/ properties. you want to UNCHECK (or CHECK... dunno which.. opposite of what is it now) the XP SP2 compatibility mode.. or something like that. there was another i heard of that would launch every app with some form of keyboard translator... allowing the user to type japanese into browsers. he was able to exclude wow.exe from that process by also going to the properties of wow.exe

good luck and let me know what you find out.