I use an iPad Air 1 (8.4) and a MacBook Pro mid 2014 13''(10.10.4)
Whenever I try to connect my iPad to my MacBook with a lightning-usb wire it starts connecting but then disconnects immediately. This process is repeated multiple times a second and even crashes my MacBook.
As a result, I can't move the mouse or write with the keyboard anymore. Animations, slideshows or videos still continue in the background, but even after I close the display and open it again, only the cursor for the password input blinks, but I can't enter anything. Hard-reset is the only way to recover the MacBook.
The iPad behaves like nothing happened and just continues working.
Sometimes it just holds connection for a minute but that's only very few times.
I tried with different 10.10s and wires, but it never works.
As it turns out, it's a specific problem of one USB port go my MacBook, which usually works just fine, but now causes trouble.