I recently purchased this Portable (iomega) 500GB hard drive. I just realized it only works on my Mac's USB ports, but not with my USB Hub... Does it exceed the power limit of the USB Hub? I don't see how it is possible, because I currently have nothing else plugged into it, and it uses a power adapter. It worked with my old Hard Drive, which is big and uses a power adapter. Now it doesn't seem to work. Also I tried on just a USB adapter that makes the cable longer, still doesn't work. Only the MBP ports work! However, the hub works for things such as phone charger, and speakers right now. What is the problem?? Thanks.