help with javascript cookies - geocities is weird

ok i have proven that there are no flaws in my script (you might remember it was the one about the midi selector) because i finished it offline and it works perfectly. i upload it to geocities and rename all the stuff to the names for the files i use on the net and it doesnt work. after searching and searching just to find that my script has no errors. The reason the midi isnt playing is that geocities has already set a cookie for my page (i think it is what makes the popup window work) and obviously with all those extra charachters it cannot recognize the midi file. is there any way to give a cookie a name that you can acces later?