I've been using my iPod touch for about 5 months now. its a 16gb and it has about 8 gigs free. but lately, its been lagging when I go to do things like check my email. it'll just freeze up for a while. and, while I'm typing, the keyboard doesn't move with my finger; it just stays on one letter and sometimes I have to reboot it or wipe the iPod completely. Has anyone else noticed this problem? ive tried taking some video off - it goes a little bit faster but its still pretty unbearable. Help?