As soon as she began publishing stories about fast and furious would be my guess as to when this hacking began. My sense is DOJ was interested in her sources within the government, especially in ATF and the legislative branch.
I wonder how this correlates with the screaming match she got from the White House dude, where he said the Benghazi issue was over.
The computer turning itself on and off sounds familiar. I had that happen to me a couple of times. In my instance, I think it was to get rid of what I had just typed, to set me back in finishing an affidavit I was working on. In her case, anything that let her know she was being watched is probably more likely to be for intimidation purposes.
Memo to Cheryl:
Next time write your Benghazi articles on an Underwood Pica Upright, and leave a bunch of misleading disinfo on your computer for the NSA hacks to find.