Why does my external hard drive no longer work

I have a toshiba 1tb external hard drive on which I back up my Toshiba lap top. This morning when I tried to do this both USB ports on the laptop died. Thats a very short explanation for what has taken some time to establish. To get them working again I have to reboot the laptop & then I can use my wireless mouse & keyboard etc. Attach the harddrive again everything dies.

Now the point that got me to this board is that I gave my hard drive to a colleague to copy some files (which he did) but he runs a mac! Has his mac killed my hard drive & done something that somehow means when it plugs into my laptop it kills the USB drives on that too?