I have a brand new 27" iMac and a brand new WD My Passport 2.0 hdd. I plugged it in, formatted as a mac format, didn't install any WD software/drivers and then set the drive in 2 partitions, one for TM and the other for storage. The drive randomly self ejects. There is no rhyme or reason as to when, but it's always seemingly within 30 minutes. Sometimes it immediately reconnects but other times I have to unplug and plug it back in. I've tested on a work MacBook and it had no issues and stayed connected. I have switched USB ports several times with no differing results. I'm new to mac so unsure if this is a setting I need to change or what. Any tips/advice is greatly appreciated, thanks!