Guys..I got the problem backing up my iPhone 4 because of this error "ITunes cannot backup iPhone because a backup can't be saved on the computer" since yesterday. I didn't have this issue two days ago after I updated my IPhone to IOS 4.21. I try googling for solution and follow most of the advice such as running Itunes as administrator and deleting all previous backup file. Well, deleting backup file did remove the error but It took me the whole night to backup and it hasn't even finished the backup. the backup file for the whole night that was created only about 519MB, I've lost patients and stop the backup. Btw, my IPhone data is about 19GB. I hope someone can help me