Ok, so that setup points several possible causes.
1. Your motherboard can not manage to give enough voltage/el. currency and empower the device correctly and thus cause that message and act like crazy.
2. Its possible that your USB mass storage driver got corrupted and act strange when you use ports. (uninstalling it then install again for fixing)
3. Sometimes when time passes jacks got their clutch weakened from often using and because of that usb port often can`t understand what is mounted device in first plugging.
I recommend you to buy usb extender and mount it to some of back usb ports. And because of 2.5"hdd the lenght should not excess 1meter. Btw that thing is only 3,4$ in most country's