I have a 500G Verbatim External hard drive. I googled how to format and partition it so that it would work with my mac. I used the disk utility and it went just like the instructions said. It causes the mac to hang up in the middle of programs when it is plugged in. It does not want to eject properly and now the screen is stuck on "scanning".

Computers & Internet - Verbatim - VER95327 USB Hard Drive