I'm sitting here nodding my head vigorously at all of the above hehehehe...my 1 yr old is just the same. Instead of saying no etc i've tried to just remove her from the 'bad' or dangerous thing she's doing without any fuss, and give her something else to do straight away. 9 times out of 10 she's happy to play with the new thing (usually a couple of pieces of old tupperware and a wooden spoon!!) and forgets about the power point or bookcase she was about to rummage through. I just found that making a big fuss over it seemed to imply to her that it was a game and it was funny to her to keep doing it as we went through it over and over again. She didn't sense the frustration in us just thought it was fun! As she gets older i will try again to do the reasoning thing, i've done the consequence routine as mentioned by someone above, with my eldest daughter and it worked great during her toddler years. But when they're so young, like under 2, i just don't think they have the ability to truly understand what you're trying to explain to them. Thats just my experience anyway :-)

Best of luck to us all!! hehehe