your itunes library cannot be saved

I keep getting "your library cannot be saved as you dont have enough access privilages for this operation", even though I have checked that all files in itunes have read write permissions ticked and i also always right click and run as administrator . just lately I have also noticed .TMP files apearing in itunes folder and today i ran task manager and found that it is a *32bit version of itunes using a very lage amount of resorces playing nothing and downloading nothing, running on my Windows 7 64 bit it was preinstalled on machine so would of assumed it would of been a 64 bit and has been updated as newer versions came out could itunes 64 bit update itself with a 32 bit version ? . Now getting error saying there's not enough memory it has 750gb free space . Is running a 32bit version of itunes problem No1 if so when i uninstall it will the 64 bit version accept the 32 bit Library.itl file . Dont really want to have to rebuild library again ps running norton 360 if that makes any difference . Thanks in advance