i just got a 64gb sandisk from amazon..
Amazon.com: SanDisk Ultra 64 GB MicroSDXC Class 10 UHS-1 Memory Card with Adapter (SDSDQU-064G-AFFP-A): Electronics
formatted it on my phone...
it works fine in the usb reader on my computer. reads quick, writes quick. when i put it in my phone empty, it is fine. but if i toss it back onto the computer and copy my music from the old sd card, it slows the phone completely, and then if i try playing any music, it does some wierd things with the screen, and shortly after, completely freezes. is it safe to assume i got a bad card? could it be that i have corrupt files in my music folder?